Here's a really good general overview of what is involved in a setup. Not a lot of in depth minutiae but plenty of info to get a good grasp on the purpose and methods. There is also a link in there to a very good string changing tutorial which pretty much covers the important aspects of that chore in a nonthreatening manner that anyone capable of playing a bass should be able to understand and follow.
http://www.studybass.com/gear/bass-setup/bass-setup-intro/
http://www.studybass.com/gear/bass-setup/bass-setup-intro/