if you play loud enough, nobody can tell you're screwing up.

I've been playing guitar for 25+ years, and except for eight lessons I am entirely self-taught. I also play a few other instruments. The only thing I've discovered that makes you get better (on ANY instrumet) is this:
Repetition, repetition, repetition. And when you're done with that, go back and repeat the whole process.
I have never seen ANYBODY ever pick up an instrument and master it from day one. Even the so-called "natural" musicians only get good at an instrument by practicing the same, boring routine stuff over and over. Hell, just tonight I practiced playing scales for five minutes, and I STILL think I suck at them!
The guitar is a difficult instrument to master. In order to play it, you have to contort your hands into weird, unnatural shapes. It takes some time to get your hands used to being in those positions. But if you keep at it, you'll get used to it, and it will become easier. Eventually it will become second nature, and you won't even notice you're doing it. Then you can tackle singing and playing at once. And maybe get one of those Dylan-type harmonica holders, and start blowing harp, too.
Keep with it. Be persistent. And don't worry if you can't hold down all six strings of an F chord at first (nobody can).
Oh, and don't forget to HAVE FUN! If it stops being fun, quit for awhile and come back to it.
GOOD LUCK!