If you want to use this with a lot of users, create a new profile field and note the profile id # and add this code into your postbit template (mine is 19).
HTML Code:
<!-- begin img -->
<br />
<div>
<if condition="$post['field19'] != ''">
<img src="$post[field19]" />
</if>
</div>
<br />
<!-- end img-->
There is more on conditionals here:
http://www.vbulletin.com/docs/html/m...e_conditionals