mgbt on Nostr: how to post img?

{ "id": "e4fc12cd7c4175a49d5d4382068f5464376c098bb1cb8d35a9bea1671d1435ef", "pubkey": "15628a5a53a8027978c13285dc70a5e4b6156f9eb9cf8eea6c97c60cc839d01c", "created_at": 1672799994, "kind": 1, "tags": [ [ "client", "astral" ] ], "content": "how to post img?", "sig": "b2f188dccd3b04a00cb9150d8c699720cbd4837cac5a88ab4b9ae0504f0cf95b279dca49da6f019e245e4926f955b9bcecb288cc597c27f68346c9708767b47a" }