Git Command line Resources
Where should I start???
Definitely start with the git book, it's free and comes straight from the source.
Why command line???
Using Git from a gui is like riding in a bus, except if you make a mistake without previous experience with the command line all of the sudden you have to drive the bus without having ever driven a vehicle before. Oh, and it's a manual. You are better off just learning how to drive the bus from the getgo rather than put yourself in a stressful situation.
I'm a firm believer in just using the command line as much as you can. The basic tasks you will complete every day are simple and easy to learn so why not learn them if it helps you in an emergency?
If that's not enough for you maybe it doesn't really matter and I won't be able to convert you to CLI anyway.