Basically, you need to sign up to fediverser and then add your community as a recommended alternative for the subreddit. Then you’ll be able to “apply” for the ambassador. Once approved, you will be able to see reddit posts and send invites to redditors to migrate.

The first step though is to have support for PieFed communities. Currently it only recognizes kbin/mbin and Lemmy. I’m pushing the update with this, so in about 30 minutes you’ll (hooefully) be able to do all that I mentioned.