Citation or bibliographic managment programs help you:
Each program works somewhat differently, so take some time to get to know a few programs and find the one that works best for you.
Don't worry about changing a program that isn't working for you. You can export your references from one program to another easily.
This chart provides a brief overview of 4 citation management program options.
Why use EndNote?
Why use Mendeley?
Why use RefWorks?
Why use Zotero?