You have several options here at vBorg.
If you have minor issues (default features not working corretly) with your site, you can post here in the appropriate forum describing each issue (I recommend making a separate thread for each issue) and someone will likely help you get them sorted out.
If you are wanting to do something vBulletin doesn't do out of the box, that is, you need some custom coding done, you can post in either the unpaid or paid request forums. You may find that there is already an existing product that will do what you want, in which case we will point you to those, or someone will be able and willing to write some code for you.
If your needs are extensive, and you find you need to post in the paid request forum, be sure to read all the sticky threads there.