Yes, you can pin Treasuries. You just choose which picture in the treasury to make as the main one.
You make BOARDS like say for Holidays, and then pin everything you like onto that board. You can follow fellow Etsy shop owners, craft ideas...
I have to admit, I'm kind of addicted!!
Follow people who have similar interests to your own. The best way to expand, is to follow people, and keep pinning!!
Good luck, it's a lot of fun!