To begin, click on window and choose PlasticSCM
Login or signup for a plastic account. Create an account at plasticscm.com if you haven’t already. Use your unity id.
If you have old organizations that are no longer on your unity projects, in plasticSCM, you will have to migrate to update. Once there, your new project should be there.
Create a workspace. Make your repository name and workspace name and create that workspace.
Once there, add in your scene assets and then do a checkin. This will commit your assets to your scm.
Now plasticSCM is set up. It is a $5/month charge, so be aware.