Initialising a repository

git init
git add .
git commit -m "Initial commit"
git remote add origin <https://github.com/><username>/<repo>.git
git push --set-upstream origin master

Adding

git add <file_or_dir>

Commit

git commit -m "Adding new feature"

Push

git push

Branch

git branch branch_name

Checkout

git checkout branch_name

Set Upstream

git push --set-upstream origin branch_name

Merge

Navigate to your Git platform and perform a Merge request