Nobody seems to have answered your question. As far as I'm aware, your notes are broadcast to all the relays that you have selected (in the settings of your nostr client).

You can find more relays to add here: https://nostr.watch/relays/find

The more you have the more likely your notes are to be seen by others. Some relays are of course only for specific things or require payment to join.

I'm also new here, but I hope this helps!