Hey Stiggstogg, thanks for checking out our project!
In order to start, you need a web3 wallet like Metamask (MetaMask), it's an extension you can add to your web browser. Follow the instructions there and set up an account. Then, you'll have to switch to "Rinkeby" testnet, which you can toggle at the top of Metamask.
Then, you can click "connect" and Metamask will pop up and you can connect with it! You're logged in!
Then, you'll need to send yourself some test ETH (aka not real ETH) from a Rinkeby Faucet Rinkeby: Authenticated Faucet.
Add your address in the faucet and you'll get some test ETH! Now, you can head over to create NFT and generate yourself a verifiably random NFT ;) You'll also be able to see this NFT on Opensea once you sign the 3 transactions needed to create it! https://testnets.opensea.io/.
These NFTs come with Unique characteristics which you can use to battle another player active on the site. (WIP)
We'll probably polish up the site soon and drop a tutorial!