Teaching yourself is great fun! I started playing by going round to a mates house who was a few years older than I. He showed me a handful of chords and about one decent strumming pattern. Goes like this:
Beat 1 + 2 + 3 + 4 +
Down - down up - up down up.
Good luck if you can make sense of that! It's easier when there is someone in person to show it to you!
After years of playing I guess it's just natural to decide when to strum down and when up.
To start with though, try and learn one thing at a time. Eg - find lots of songs with the same chords in that you know, and practice changing from one chord to another. Once you can do that smoothly, it is easier to practise strumming because you don't have to break the rhythm to struggle with the next chord.
Don't try to learn too many chords at once either. Be content that to begin with, when you see a G7sus2add#9 or what ever, (don't know if that actually exsists), you are just going to play a G major!! It won't sound perfect, but it sound better to play the wrong chord cleanly and smoothly than make a hash of fingering some crazy chord you'll never see again in your life!
Well. Just enjoy it.
G'luck
JE