Sus2 chords are formed with the second note in the chord lowered one step. In addition to sus2 there is sus4, that is some more common. If you see instructions to play a chord like Esus or Asus it is usually not sus2 but sus4 chords.
The shift from the original major chord to the sus chord is for the most part easy done. Below you can see that the difference from a major chord to its "sus2 version" is not very big:
C major Csus2
There are two differences: 1) on the fourth string the tone is lowered one step from E to D, 2) you don't play the highest open string because this is an E note. When shifting from C to Csus2 you should therefore only lift the long finger and don't move the rest of the fingers.
The Tom Petty song "Feel A Whole Lot Better" makes use of sus chords in a riff:
A - Asus2 - A - Asus4 - A - Asus2 - A.
The song also includes the chords E , F#m, B, Bm, D and G.