how do i get packs to add?
There's some packs in this comments section, some packs over on GameBanana, some pack creators have their own itch.io page (like AlizerinRed's Pokémon stuff), or people post packs on the unofficial Discord server created by HProtagVtuber.
After unzipping a content pack, you put the content in the corresponding folder (there are buttons in-game that will open the proper location for you).