Question on branch rules & workflow of files

[School-learner]

I spent a bit of time playing around with the latest version. I managed to get my Unity project into the sourcetree but I don't see any rules about naming conventions when branches are created. I also want to know why my script files just disappear when i commit and push. My screenshots are as below. If anyone there knows how to use source tree, some information on the rules would be nice. Thank you.