How do i do the iron man intro with a floyd rose?

[queen wadi]

Bend the body of your guitar by holding the headstock/neck and pushing the body towards you with with your elbow. Might cause other issues if overdone

[ebon nymph]

The intro? That's just pushing down the low "E" String behind the nut usually.

With a Floyd Rose, just play an open E note and pull up on your tremolo bar.
If you don't have a Whammy Bar on your guitar for some reason, just push down on the bridge (on a Floyd Rose that's not locked down).

Another way to make the effect happen is to use a whammy Pedal (which is a great pedal to get anyway).