The purpose of an Etsy Treasury is to promote and give credence to other designer/makers who make things that you admire and are inspired by. You can theme it, comment on it, edit it and you can make as many Treasurys as you like. It is not meant to be a self promotional tool so when you create your Treasury it is not expected for you to add your own personal products to it. It’s a celebration of other peoples work, and it feels nice knowing that you are helping to promote someone else’s business!
When you have made a Treasury an automatic email notification is sent to the designer/makers to let them know that they have been featured which is a nice touch.
Here is a Treasury that I created, with the theme of Peach:
And here is a Treasury my Opulent Reed Diffusers have been featured in, with the theme of Home: