In terminal

git branch <name of branch you want to create>
git checkout to move to ^^^
then you can change code -add nav bar or etc or change some code
git status to see branch
git add .
git commit -m "testing"
git push -u origin <name of branch you created>
then go back to github and press create pull request then merge pull request
git checkout main
git pull to go back to main with all update