Get you started with Git from zero (note that if you already use Git, this workshop will be too basic for you). We'll work with GitHub (Desktop) and have a look into git on a command-line level. 

Introduction, set-up & configurations
Working locally: Create a repository, clone, edit, staging commits, commit & push
Working with your history & logs
Working in a project: Forking, branching & pull requests
How to version control your code in Rstudio with GitHub