You need to look at the code for the link. It should look like this:
Code:
<a href="http://domain.com">This is a link to domain.com</a>
or this:
Code:
<a href="directory/anotherdir/somefile.html">This is a link to another page on my site</a>
If your Yabb is on your x10 account with your sitebuilder site, then you use example #2. If your Yabb is somewhere else, you need to use example #1. Technically, you can always use #2, but if you change your domain name (by changing hosts, or using a different domain) you will have to change every link on your site.