Citation or bibliographic management 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.
Use the first comparison chart to get a brief overview of 4 options. Use the second chart if you'd like a bit more information.
Why use EndNote?
Why use Mendeley?
Why use Zotero?