If you already have the Sitefinity Project Manager, then you have done at least half the job of having a new project. There is a very straightforward process, which you can follow and I am sure that once you see it will feel just natural to you.
To do so, please follow the documentation instructions located here (link here).
I am also sending you two short videos, which will also help you in achieving that task quickly:
Let us know if you encounter any difficulties while following the procedures described above