saved project

I'm new to Illustrator so I'm taking a Skillshare class to learn.  In the class he is asking for us to save projects and then at later times reopen those projects to change/add to them.  The problem I'm having is that when I save a project and then reopen and try to make any changes, even if it's just selecting the art work portion, it won't let me.  It drag the background with it and won't let me select just the art work. I've tried unlocking all layers so I don't believe that's what the problem is.  I think it's probably a really simple answer or something I'm doing wrong when I save proects.  Can anyone help?