[CyberAlien]

In your case you need to edit one of forumhome_forumbit templates, most likely forumhome_forumbit_level1_nopost. To start lets convert who's online box to use rounded corners as its the simpliest part to do, then you'll need to convert all other tables similar way.

In forumhome find this:

<!-- what's going on box -->
<table class="tborder" cellpadding="$stylevar[cellpadding]" cellspacing="$stylevar[cellspacing]" border="0" width="100%" align="center">
<thead>
	<tr>
		<td class="tcat" colspan="2">$vbphrase[whats_going_on]</td>
	</tr>
</thead>
<if condition="$show['loggedinusers']">
<!-- logged-in users -->

and replace with something like this:

<!-- what's going on box -->
<table border="0" cellspacing="0" cellpadding="0" width="100%">
	<tr>
		<td width="20"><img src="$stylevar[imgdir_misc]/corner_left.gif" width="20" height="20" border="0" alt="" /></td>
		<td width="100%" class="tcat">$vbphrase[whats_going_on]</td>
		<td width="20"><img src="$stylevar[imgdir_misc]/corner_right.gif" width="20" height="20" border="0" alt="" /></td>
	</tr>
</table>
<table class="tborder" cellpadding="$stylevar[cellpadding]" cellspacing="$stylevar[cellspacing]" border="0" width="100%" align="center" style="border-top-width: 0;">
<if condition="$show['loggedinusers']">
<!-- logged-in users -->

You'll need to make 2 images for corners. In example above I named them "corner_left.gif" and "corner_right.gif" and that code assumes images are in "misc" directory of your style's images and images are 20x20 pixels.

So create two corner images that would match design and then adjust that code for your images. When you do that apply same changes to other tables that you want to have rounded corners.