add data into selectfild with ajax

[ragtek]

i have a selectfield:

<form action="musikcp.php" method="get">
<select name="kategorie">
<option value="1" class="" selected="selected">kategorie1</option>
<option value="2" class="" >123</option>
<option value="3" class="" >123</option>
<option value="4" class="" >mein test</option>
<option value="5" class="" >123</option>
<option value="6" class="" >23</option>
<option value="7" class="" >23</option>
</select></form>

and a form:

<div class="vbmenu_popup" id="neuekat_menu" style="display:none">
<form action="musikcp.php" method="post">
<table width="200px"><tr><td class="alt2">Name:
<input type="text" name="katname" />
<input type="hidden" name="do" value="dokat" />
<input type="submit" value="speichern" /></td></tr></table></form>
</div>

how can i add the new cat wich i input throu the form to the select part without reloading the site?