Get an instructional book or hire a guitar teacher to learn a few basic punk chords. Start with power chords, which are an essential element in punk guitar playing. Power chords are simple and relatively easy to learn, and are the basis of many classic punk tunes (see Resources). A power chord is generally played in eighth note rhythm with just two or sometimes three fingers on the fretboard. Punk guitarists generally play power chords in downstrokes to give the music a chugging sound. If you learn just a few power chords, you can play around with them to create some simple punk tunes. Once you're comfortable with power chords, try learning barre chords. Barre chords are similar to power chords, though they use more strings. Finally, learn about open chords, which are also used in some punk songs, though not quite as common as the standard power chords. Once you learn these three types of chords, you'll know the basic blueprint of punk guitar playing.
You can then move on to learning some basic techniques such as palm muting, fret muting, slides, hammer ons and bends. These techniques are handy, but a good rule to remember when playing punk guitar is to keep it simple. Don't overdo it or try to add too many tricks and techniques.
Once you've learned the basics, you're ready to hone your skills. An easy way to do this is to learn from the punk masters themselves. Get guitar tabs for classic punk tunes and learn as many as you can. Buy punk CDs and play along with them.
It's important to keep in mind that when it comes to punk music, it's as much about attitude as it is musical talent. Punk isn't just a type of music, it's a state of mind. Some of the most successful punk bands, such as The Sex Pistols and The Ramones, were not technically expert musicians, but they had a stage presence. They had the punk attitude, and they projected that attitude in their live performances. When learning punk rock guitar, be sure to study not just the music but the way it's presented. Go see live punk bands whenever you can, and watch recorded footage of classic punk performances. Don't copy anyone's style, but use examples from the past to build your own playing style and persona.