How to make a copy of a solution

I admit I am a clueless newbie.

I have a project (I keep forgetting to call it solution) that I want to make a copy of. I looked at save as but none of the options seems to make sense. So I make a copy of the folder and renamed it and it still had the old names. So I made a copy then renamed it  and the sub parts and that one wouldn't open. So I deleted the folder and now SharpDevelop still tries to use that name and complains it isn't there (when I click on save as).

How do I make it go away and how do I copy a solution?

Lee