Hi,
my first post here... what a fanastic site! I am 60 yrs old and picked my first guitar up at 16! Been round the guitar block several times and had a ball!
Strumming? Just keep doing it as other people say but one tip is... to familiarise yourself with a piece first DITCH YOUR IPOD! You said you had difficult picking the rythms out. PLay them on a CD player not an IPOD.... fiddle around with the left and right balance and you will be able to bring the rythm guitar out of the background and you'll be able to focus on it. And when the sound is in the room and not right in your ears over an earpiece you should be able to find it. Good luck.
Ian