You're not an idiot, sydney, you're just new to all of this. I was too, a few months back, when I first tried to install YaBB 1 Gold. MAN what a headache! But once you start to realize whats going on you'll realize its not complicated, its just one of those "Think Outside the Box" type problems -- in other words, you have to be open to thinking about the web in new ways, take things one step at a time, and keep asking for help.
CHMOD is an FTP command that works on Unix (or Linux) based servers, and the number "777" means that the website admin, the "group", and the world each have READ, WRITE, and EXECUTE permission.
Don't worry about all that stuff so much though. I have to think that maybe the reason you're getting a problem is because you haven't done the CHMOD bit -- what FTP program are you using? If you're using WS_FTP its a little weird to figure out how to do the CHMOD command. If you're using just regular command line FTP (like through the MS-DOS prompt) then you type:
site chmod 777 MySEdirectory
Let me know if this helps -- if it confuses you then just pretend you never saw it