How to use Xcode 6 debugging for single C file

Xcode 6 has Run, build, pretty much everything in debug menu greyed out for a single C file that I open in Xcode. This is a prebuilt program. I wish to debug it, and make changes to the file, but it seems that it must be a project to use debug functionality. Is this true?

I am in university so I wish to have single files as they are submitted like that. If it is not possible to debug on Xcode, are there any better recommendations?

Thanks.