You can’t! Most Aero features have been removed from Windows 8 and that (sadly) includes Flip 3D. There was talk of this feature being tied to the Windows theme you were using, but I have tried several that used to include Aero Glass frames and none work (even though it did work on the beta’s).
Note that there is an ugly work around to get Glass to function in a minimal way but after running it for 2 minutes I reverted so I would not waste your time with it.
On the slightest of bright notes Aero Snap still works and you CAN re-enable Aero Peek (see screen shot below)
… and one more thing which you might have guessed already; the word AERO has been removed from all things 8 (so we now have SNAP and PEEK