I don't play punk, but you could try writing songs and see what you come up with. If you're not ready for that yet, don't sweat it. You can just play covers until the songwriting becomes good. Also, practice regularly, otherwise you might sound bad, even if most songs you play are only 3 chords or so.
"Notes are expensive. . .use them wisely"-B.B. King

"It's been very important throughout my career that I've met all the guys I've copied, because at each stage they've said, 'Don't play like me, play like you."-Eric Clapton
Although I'm not a punk fan, I wouldn't knock it completely. Especially if you are a beginner band considering punk is going to be easier to play than other styles. Your best bet is to read some of the information on this site. Just browse forums, stickies, and articles. You'll find what you are looking for most of the time.

Here are some basic tips I can give you:

1. If this is your first band, it would be beneficial for you to go to other bands' practices. You can see how they work out things and get stuff done. I once went to a hardcore punk bands' practice that claimed they were big in the area. At practice, they talked and joked around for about an hour, played through the set once (about 30 minutes) then stopped to go to a chinese restuarant. I think that band was together for about 3 months after that and last time I saw the singer he was working at a Subway.

2. Visit as many shows in your area as possible and talk to other musicians. This is how you start to book gigs later on, so you are best to start now.

3. Don't get discouraged if things don't work out well. Most bands don't last but a few months.
I was once heavily prominent on these forums from 2004-2007, let's see how long I can stay now that I'm back.
if your playing punk, than you have to have that not-give-a-dam attitude about it, so when people come up and tell you your a poser, you can just shrug it off, because you are playing music for urself, and not them