You now have to create the new Desktops/Spaces and then add the apps while in the desired space.
- Go to Mission Control and scroll up to the upper right hand corner of your display.
- Click on the '+' sign to create a new Desktop.
- To assign an app to it, go to the new Desktop and with the app active and running in the Dock, right-click on it and move to Options and 'Assign To:' This Desktop (or All Desktops if you wish)
You'll have to do this for every app and new Desktop.
Unfortunately, it's a step backwards in initial setup when compared to Spaces in 10.6.x