Hello Laides,
Creating treasuries helps you get views, likes and expose within the Etsy community especially from your fellow sellers. It's also a lot of fun! You can create a Treasury of up tp 16 items in any theme you choose. It is basically a collection of favorites. As a general rule you do not include your own items. In this thread I am specifically asking members to create a Treasury of items from shops in this group. I find that using Etsy to create Treasuries is cumbersome but if you download Treasure Box by Brittany's Best it makes it sooo simple! I hope that helps! Do you have any specific questions about making Treasuries I might be able to help with?
Christy