I found the making groups you talked about, but can I move previously created events into the group?
Just select the events you want (using the 'margin' to the left of the event), and drag them in. To add a new layout, right click the application in the project bar, and click Add Layout. You can use system actions to move between layouts, and that acts as levels. You can also use separate event sheets to organise your events, and include them in other event sheets, allowing a write-once, use-anywhere solution.