Using hexadecimal and Metamask, you can encode permanent messages onto the Ethereum (or any EVM) blockchain. People will then be able read these messages on Etherscan if they know where and how to look.
So, you've been doing too much PvE and want to get into the on-chain PvP scene. Be wary traveler, this is a lonely environment to be in if you're playing solo. You will spend months building to upkeep your infrastructure to stay competitive, unless you find a very niche strategy. However, the booty is high and mighty if you manage to pull it off! If that sounds like something you want to do, continue on.