1. Get a nice, cheap distortion pedal, a must.
2. Tune your guitar to drop D.
3. Get a hard, small pick.
4. Practice strumming while "Palm Muting" which means you place the flesh of your hand against the bridge, produces that Chugging tone you want.
5. Practice your rhythms, preferably with a drummer.
6. Come up with a song. For your style, a rhythm guitarist basically plays opens, with an occasional blast of semi-music. So, chug away, then for one beat, put your finger on any fret you like, barring it, and play that with feeling. For a Norma Jean time squeal, play the 4th fret on the high B, and open on the High E.
7. Kill a man. It'll help with lyrics.
8. Record, and sell!