Create a new branch:
git branch newcarservice
Move to the new branch:
git checkout newcarservice
Update the code and commit changes:
git commit -a -m "newcarservice"
Push the changes to GitHub:
git push -u origin newcarservice
Create a Pull request on GitHub and follow the workflow.
Merge the branch on Github is everything is OK.
Then pull the new main version:
git checkout main
git pull origin main
If necessary delete the branch:
git branch -D newcarservice
git push origin --delete newcarservice