Need Help with Defense Pre-Snap

[MPR_NY]

I need major help, i'm gonna play a friend online talkin mad trash. He says offense wins games while i say defense does.

I need to know the basics of certain defensive pre snaps.

This is what i know:
Press Coverage - Throws off timing of recivers with QB etc.
Back off - Hang back and make sure not to get burned deep.
Show Blitz - Pretty much show blitz and fill up holes and line but dosen't nessarily mean i'm going to blitz.

i know how to audible


What i need help with:
Align - o_O ??

Crash Line - i don't get why there are options for that...isn't it just "crashing" the line? and that does each direction do?

Spreading Safties - how do i do that?
Line and LB shifting - when is it good to do that? ( i know certain formations call for that but i jus need a general idea and i can improvise)

what else should i know for defenseive pre snaps and stuff.. help me soon.


Thanks.