What do I have to do after I buy SOL?

You have to send it to the Solana wallet that will be connected to the Star Atlas Marketplace.

To use your SOL in the Star Atlas Marketplace, we recommend using a Solana wallet like Torus. The Torus wallet is a gateway to a decentralized ecosystem where users from all around the world can log in using a web 2.0 social account and freely interact with web 3.0 user identities. Another popular wallet is Phantom which has an IOS mobile application and allows you to see your NFTs in a separate section. The video below showcases the steps involved in utilizing your SOL and participating in the Star Atlas Marketplace.