Hello.

I'm looking for a way to create a user that has the permissions to do this, and absolutely nothing else:
Scp files to their $HOME dirs on my system from other systems.
Log in and have 777 permissions to their own $HOME and not be able to access any other part of the system, like my $HOME, for example. Of course, they should be able to scp files back to their own computer.

I'm pretty much a total newbie to user administration and permission handling(I know how to use chmod and /etc/passwd, but that's it basically), so i realize this may seem like an obvious question.

Any ideas?

You're probably looking for a way to chroot certain users into their home directories. There's a tool called JailKit that can help you get chroot jails set up. I've never used it personally, but it looks quite good.