If you are new to working with a CLI, it is well worth following up with the help of some online resources to improve your skills. Any serious software development will probably involve some work at a command line at some point.
Since both Git and Mercurial are open source, there are lots of great, free online resources available. The following are some good sources to get you started:
- Learn all about Git, download free GUI clients, and even get free online access to The Pro Git book (by Scott Chacon), available through a Creative Commons license: http://git-scm.com/book.
- You will find an online interactive Git command line to practice on at https://try.github.io/levels/1/challenges/1.