I don't see it anywhere on my screen, no matter what I click. Is it because I don't have premium?
If you hover your mouse to the left of a Project, you should see three horizontal bars and your mouse pointer should turn into a 'four headed arrow'; click and drag the Project into a new position.
You can do a similar movement with Tasks, but Tasks are automatically sorted first by Due Date (and Due Time, if any), then by Priority. There have been reports of sorting 'breaking' by manually sorting Tasks.