won't let me create new movie

What version of OS X is on your Mac and is that iMovie 10 with no added updates? iMovie 10.1.2 is available to update to.

You should be able to click on "Projects"

Gets you to this window:

Click Create New and that would be a new Project.

Are you doing this specifically and it's not working?

I'm having the same issue. I was able to create a Project, went to create another one and now nothing happens.

Had to close and reboot a few times. Then I got a message when opening iMovie saying that the Library was rebuilt from backup. That seemed to fix things.

I have this same issue. I found a work-around until it's fixed. Create a New Movie, then Choose Settings (far right middle ; see image). Then, click on the "No Theme" button, then pick a Theme.