It is not that complicated,
The concept is simple - different variable or different value of a variable invokes a function associated with it.
Example...
<?
if($ind=="delete")
echo "Delete Record";
if($ind=="add")
echo "Add Record";
if($ind=="update")
echo "Update Record"
//NOW COMES THE FORM
echo "
<form method=post action=$PHP_SELF>
<select name=ind>
<option value=delete>Delete</option>
<option value=add>Add</option>
<option value=update>Update</option>
</select>
<br>
<input type=submit value=\"Do It\">
</form>";
?>
Of course, replace echo statements with your own generic functions. If you'll be doing database querying, place $conn=mysql_connect($host, $user, $pass); $db=mysql_select_db($database, $conn) before the control structure.
Hope that helps,
Di