Downloading Code for Use - Just learning

I am very new to this community, and to programing. I have a Jetson Nano Developer Kit, and I am interested in using some of the open source code on Github on my new kit. Is there a training link that I can go to and learn how to do this. Currently all I can find is info on how to start threads and upload ideas…that will come, but nothing I can find on how best to download the code from github to my developer board. Any help?