Hey dude the best way i think of describing palm muting (Pm- as referd to in tabs) is to say to its liek dampening the strings you put the bridge of your hand over the bridge of your guitatr. to try and practise it hit like the top E then put Palm(bridge) of your hand over the bridge of your guitar and hit the top E again and you will notice the difference. it just gives it a muted sound lol. Hope tht helps dude you could try using pm for power chords or something