The 3 relays are:

wss://relay.mostr.pub

wss://relay.shitforce.one

wss://nostr.coinfundit.com

I think it has to do with adding those and then looking up your profile on mastodon, following it, and then that bridge should generate your posts from the desired nostr to that linked mastodon.

I wish there was a way to consolidate all these fedi accounts into one key, as my understanding this was just a real quick way to get a mass bridge working.