Make changes in your IDE.
Make a feature/** or bugfix/** branch (git branch feature/adding-icon)
Checkout that branch (git checkout feature/adding-icon)
(OR DO BOTH AT ONCE! :D ) (git checkout -b feature/adding-icon)
Stage the changes you would like to commit. (Selecting which files you would like to create a snapshot of) (git stage ./icon.png) (git stage --all)
Commit those changes. (Creating the snapshot) (git commit -m "your message here")
Push (push them up to github) (git push)
Push the branch ( git push --set-upstream origin feature/** )
Create the Pull-Request (PR)
Notify your team, have them review your code.
Once the admin of the team approves your work, it gets merged.
It's now in the develop branch