Watch the Downstrokes online guitar lesson by Chris Buono from 60 Electric Guitar Techniques You MUST Know
It's safe to say that just about every stringed instrument newbie's first move on their axe of choice is a downstroke. That's a great start since many more downstrokes are to come!
I can't stress enough how important it is to establish a connection between this technique and the concept of rhythm and playing in time right from the start. Play along anything that has a consistent pulse. That's what a beat is.