Updated for 7.0
On the left-hand side of the screen in the navigation bar EVENTS, select Parade. This will take you here:
In the bar at the top of the page, select Lineup. This will take you here:
To edit the parade lineup, click and drag different floats to the desired location.
To delete a float from the lineup, click the trash icon located to the right of the desired group.
These are samples.