You need a Bitcoin Lightning wallet of some kind. On desktops you can e.g. install Alby (https://getalby.com/). Follow the setup and you’ll get a lightning address which looks just like an email address. Then you can receieve satoshis to that address. More about the lightning address here: https://lightningaddress.com/.

On nostr, many clients let you add this lightning address to your profile which makes it easy for strangers in cyberspace to tip you satoshis. Idk what nostr client you use but e.g. on Damus, you can go to your profile and click the “edit” button. There will be a field with the title “Lightning address” or something, this is where you put your lightning address.