Quote: "hey, might sound stupid, but what does it mean when you say you cant "build" with FPSCF?"
It means you cannot build the executable file. (YourGamesName.EXE)
Quote: "hmm? Like, you cant capy it on a disk, or make multiple levels, or what?"
Like a person would not need to have the FPSC engine to play your game.
They would just run the executable file (application) like another other program.
You select all the levels you want for the game in the build process.
The resulting EXE is your game, and it puts that and all the files it needs to run in the MyGames folder for you.
You can then package all of the files and the exe together for asset protection or installers, but that is another subject.