its a stupidly hard thing you do with your tremolo arm i am currently trying to learn. its not a basic though its damn hard to do right.

play a note, grab ur Trem Arm and pull it so u lift up ur guitar with it and shake it like ****, i think thats how you do it. I can't so i kinda just press it down n back to normal damn fast and damn hard, it should make the note squeel abit like a pinch harmonic but more violent really.
a dive bomb is normally done with a locking trem system, basically its when you hit the note and manipulate the note with use of the whammy bar, bend it in and out of keys etc, think some of the stuff by van halen, he pioneered the use of divebombs really.........or something like star spangled banner by hendrix there is a lot of whammy bar usage in that
Satch's divebombs are awesome, he hits a harmonic above the pickups on 2 strings (past the end of the fretboard), pulls it up and dives it all the way down
A screaming dive bomb is when( you have to have a Floyd Rose btw) is when you hit a natural harmonic and pull up and down with the trem, sounds wicked.