I will start by recommending GitKraken , an open source, cross-platform git client. It is not strictly FLOSS because the developer is a private company called AxoSoft (DISCLAIMER: I am not affiliated with this company or any of its partners). However, I still recommend it because it is incredibly user-friendly. I use it to synchronize my projects on different hosting services (GitHub, GitLab, and BitBucket) using a clear GUI. A YouTube tutorial on how to use your GitHub repositories via GitKraken can be found here.
Give it a try!