Making a collection in the 3d warehouse

So far i have uploaded 8 models to the 3d warehouse and would like to know how you make a collection, I’m not sure how that works as i am sort of new to uploading models to the warehouse. Do you need to upload the models into the collection you made or do you select the models you all ready uploaded.

Creating, editing, or removing a 3D Collection — SketchUp Help
http://help.sketchup.com/en/article/57148

Create a collection and Edit 3D collection pages — SketchUp Help
http://help.sketchup.com/en/article/166141

thanks for the help.