If you’re wondering where to start when you first open Google Wave, try these 11 simple tasks that will give you a feel for the interface and the design decisions that went into it. For example, Tip 7 is:

7. Creating Folders in Google Wave allows you to create categories for your Wave documents. This is also useful to clean the Google Wave Inbox of older Waves and file the Waves documents.
   To move a Wave document to a Folder: click on a Wave document and dragdrop it to the Folder name.

Google Wave Tips

Also check out this simple tip to add video to a wave