Hey, great first post! Love the layout :D

Regarding your rank, there's a wonderful resource known as GU Decks that provides all kinds of resources you can use to refine your decklist, lookup card themes, and even track your own progress.

While it's harder to do at first, one of the first major improvements to a deck is typically getting a second copy of the cards you play most. Since you're playing Nature, that Giant Pangolin you pulled is a solid upgrade to most Nature decks, and staples like Canopy Barrage are commons you'll hopefully get two of as you earn more Core Packs.

Otherwise, welcome to the community!