Steps

1. Create a new project on GitLab
2. Choose the + button on the menu bar and add a project name and then click "Create project"
3. This will give you a new project address, choose the https version and you will have something like:
4. https://gitlab.com/MyUserName/my-project.git
5. Create a Git repository in Android Studio
6. In the Android Studio menu go to "VCS" -> "Import into Version Control" -> "Create Git Repository" (select the root directory of your project)
7. Add remote
8. Go to "VCS" -> "Git" -> "Remotes" (copy paste in the https address you got from GitLab in step one)
9. /!\ You may need to log in with your GitLab username and password!
10. Add, commit, and push your files
11. /!\ Make sure you have the top level of the project selected. If you are in the Android view you can switch it to the Project view
12. To add a new file or update one, simply go to "VCS" -> "Git" -> "Add"
13. After adding, do "VCS" -> "Git" -> "Commit" (you will need to write a commit message, something like "initial commit")!
14. /!\ Do not forget to specify an user like "xxxx " (with your GitLab pseudo and mail)
15. Finally, go to "VCS" -> "Git" -> "Push"