Watch the Sonic Color online guitar lesson by Brad Carlton from Chord Studies: Evolving Progressions Vol. 1
Here we have a I - ii - vi - V in the key of E. When you get to the B chord, which is the V chord, listen for how it wants to resolve back to the I chord. Make sure you think about the chords as well as their associated numbers. The whole goal here is not just to play the chords, but to hear the changes and chords as sonic colors, so to speak.