sätta in html taggar före och efter text

jag har ett problem. jag vill ha så att när men trycker på en knapp så ska tex <b> komma framför markerad text i en textruta samt </b> efter markeringen. jag hittade liknande, men det fungerar inte som jag vill ha det. <b> och </b> hamnar efter markeringen i det jag hittade.

nån som kan hjälpa mig?

jag skickar med koden oxå så får ni titta om ni vill.

helpstat = false;
stprompt = false;
basic = true;

function thelp(swtch){
	if (swtch == 1){
		basic = false;
		stprompt = false;
		helpstat = true;
	} else if (swtch == 0) {
		helpstat = false;
		stprompt = false;
		basic = true;
	} else if (swtch == 2) {
		helpstat = false;
		basic = false;
		stprompt = true;
	}
}

function AddText(NewCode) {
document.artikel.content.value+=NewCode
}

function email() {
	if (helpstat) {
		alert("Email Tag Turns an email address into a mailto hyperlink.\n\nUSE #1:  [url="http://someone\@anywhere.com"]someone\@anywhere.com[/url]  \nUSE #2: <A HREF="http://\"someone\@anywhere.com\"" TARGET=_blank>link text</A>");
		}
	else if (basic) {
		AddTxt="[url][/url]";
		AddText(AddTxt);
		}
	else { 
		txt2=prompt("Text to be shown for the link. Leave blank if you want the url to be shown for the link.",""); 
		if (txt2!=null) {
			txt=prompt("URL for the link.","mailto:");      
			if (txt!=null) {
				if (txt2=="") {
					AddTxt=" <A HREF="http://"+txt+"" TARGET=_blank>"+txt+"</A> ";
					AddText(AddTxt);
				} else {
					AddTxt="<A HREF="http://\""+txt+"\"" TARGET=_blank>"+txt2+"</A>";
					AddText(AddTxt);
				}         
			} 
		}
	}
}
function showsize(size) {
	if (helpstat) {
		alert("Size Tag Sets the text size. Possible values are 1 to 6.\n1 being the smallest and 6 the largest.\n\nUSE: [size="+size+"]This is size "+size+" text[/size="+size+"]");
	} else if (basic) {
		AddTxt="[size="+size+"][/size="+size+"]";
		AddText(AddTxt);
	} else {                       
		txt=prompt("Text to be size "+size,"Text"); 
		if (txt!=null) {             
			AddTxt="[size="+size+"]"+txt+"[/size="+size+"]";
			AddText(AddTxt);
		}        
	}
}

function bold() {
	if (helpstat) {
		alert("Bold Tag Makes the enlosed text bold.\n\nUSE: [b]This is some bold text[/b]");
	} else if (basic) {
		AddTxt="[b][/b]";
		AddText(AddTxt);
	} else {  
		txt=prompt("Text to be made BOLD.","Text");     
		if (txt!=null) {           
			AddTxt="[b]"+txt+"[/b]";
			AddText(AddTxt);
		}       
	}
}

function italicize() {
	if (helpstat) {
		alert("Italicize Tag Makes the enlosed text italicized.\n\nUSE: [i]This is some italicized text[/i]");
	} else if (basic) {
		AddTxt="[i][/i]";
		AddText(AddTxt);
	} else {   
		txt=prompt("Text to be italicized","Text");     
		if (txt!=null) {           
			AddTxt="[i]"+txt+"[/i]";
			AddText(AddTxt);
		}	        
	}
}

function quote() {
	if (helpstat){
		alert("Quote tag Quotes the enclosed text to reference something specific that someone has posted.\n\nUSE: [quote]This is a quote[/citat]");
	} else if (basic) {
		AddTxt=" [quote] [/citat]";
		AddText(AddTxt);
	} else {   
		txt=prompt("Text to be quoted","Text");     
		if(txt!=null) {          
			AddTxt=" [quote] "+txt+" [/citat]";
			AddText(AddTxt);
		}	        
	}
}

function showcolor(color) {
	if (helpstat) {
		alert("Color Tag Sets the text color. Any named color can be used.\n\nUSE: ["+color+"]This is some "+color+" text[/"+color+"]");
	} else if (basic) {
		AddTxt="["+color+"][/"+color+"]";
		AddText(AddTxt);
	} else {  
     	txt=prompt("Text to be "+color,"Text");
		if(txt!=null) {
			AddTxt="["+color+"]"+txt+"[/"+color+"]";
			AddText(AddTxt);        
		} 
	}
}

function center() {
 	if (helpstat) {
		alert("Centered tag Centers the enclosed text.\n\nUSE: [center]This text is centered[/center]");
	} else if (basic) {
		AddTxt="[center][/center]";
		AddText(AddTxt);
	} else {  
		txt=prompt("Text to be centered","Text");     
		if (txt!=null) {          
			AddTxt="[center]"+txt+"[/center]";
			AddText(AddTxt);
		}	       
	}
}

function hyperlink() {
	if (helpstat) {
		alert("Hyperlink Tag \nTurns an url into a hyperlink.\n\nUSE:  [url="http://www.anywhere.com"]http://www.anywhere.com[/url] \n\nUSE: [url="http://www.anywhere.com"]link text[/url]");
	} else if (basic) {
		AddTxt="[url][/url]";
		AddText(AddTxt);
	} else { 
		txt2=prompt("Text to be shown for the link.\nLeave blank if you want the url to be shown for the link.",""); 
		if (txt2!=null) {
			txt=prompt("URL for the link.","http://");      
			if (txt!=null) {
				if (txt2=="") {
					AddTxt=" <A HREF="http://"+txt+"" TARGET=_blank>"+txt+"</A> ";
					AddText(AddTxt);
				} else {
					AddTxt="<A HREF="http://\""+txt+"\"" TARGET=_blank>"+txt2+"</A>";
					AddText(AddTxt);
				}         
			} 
		}
	}
}

function image() {
	if (helpstat){
		alert("Image Tag Inserts an image into the post.\n\nUSE: [img]http://www.anywhere.com/image.gif[/img]");
	} else if (basic) {
		AddTxt="[img][/img]";
		AddText(AddTxt);
	} else {  
		txt=prompt("URL for graphic","http://");    
		if(txt!=null) {            
			AddTxt="[img]"+txt+"[/img]";
			AddText(AddTxt);
		}	
	}
}

function showcode() {
	if (helpstat) {
		alert("Code Tag Blockquotes the text you reference and preserves the formatting.\nUsefull for posting code.\n\nUSE: [kod]This is formated text

");
} else if (basic) {
AddTxt="

";
AddText(AddTxt);
} else {
txt=prompt("Enter code","");
if (txt!=null) {
AddTxt="

"+txt+"

";
AddText(AddTxt);
}
}
}

function list() {
if (helpstat) {
alert("List Tag Builds a bulleted, numbered, or alphabetical list.\n\nUSE:

• item1
• item2
• item3

");
} else if (basic) {
AddTxt="

";
AddText(AddTxt);
} else {
txt=prompt("Type of list Enter \'A\' for alphabetical, \'1\' for numbered, Leave blank for bulleted.","");
while ((txt!="") && (txt!="A") && (txt!="a") && (txt!="1") && (txt!=null)) {
txt=prompt("ERROR! The only possible values for type of list are blank 'A' and '1'.","");
}
if (txt!=null) {
if (txt=="") {
AddTxt="";
} else {
AddTxt="

1. "+txt+"

";
AddText(AddTxt);
}
}
}

function underline() {
if (helpstat) {
alert("Underline Tag Underlines the enclosed text.\n\nUSE: This text is underlined");
} else if (basic) {
AddTxt="";
AddText(AddTxt);
} else {
txt=prompt("Text to be Underlined.","Text");
if (txt!=null) {
AddTxt=""+txt+"";
AddText(AddTxt);
}
}
}

function showfont(font) {
if (helpstat){
alert("Font Tag Sets the font face for the enclosed text.\n\nUSE: The font of this text is "+font+"");
} else if (basic) {
AddTxt="";
AddText(AddTxt);
} else {
txt=prompt("Text to be in "+font,"Text");
if (txt!=null) {
AddTxt=""+txt+"";
AddText(AddTxt);
}
}
}