The dream fast pass is, in itself, all the fastpasses you need - you don't need to collect them. It is one fastpass per ride. There are little tabs on a big plastic card that you wear on a lanyard. Each tab is for a specific ride, and you give that to the fastpass collection people - while wearing your lanyard/plastic card.
If you have the dream fastpass you can still collect regular fastpasses as you normally would (but they're not necesary to go on once). If you only desire to go on the ride once (with the DFP tab), you don't have to wait for any specific time like you would with a regular fastpass.
Hope that clears it up for you!