Rails show content specific to user group, adding user groups

I'm currently new to Rails and I'm making a Rails site that allows users to create a project, and inside the project, users can make lists, submit files, etc. I am using devise for my user authentication service, and I was looking for the most efficient way to structure this application.

I would like users & projects to be generated when they sign up. Content will show to its specific project. I would also like the ability to add additional users to a project.

I was looking at the current_user in devise but I'm not sure how to implement into this structure.