I know!! Lol you have to set up a LN wallet first. If you are a beginner you can use a custodial like wallet of satoshi or alby. Eventually you want to use your own node when you’re ready and connect a wallet through your node.

After you download and setup and account you will get a name like “wallet@satoshi “ then you put that in your profile. There is a little button called “edit profile” there you can see the “Lightning address “ or something like that. In there you paste your “wallet@satoshi “ address