Is there away to send the same message from your দেওয়াল to your অনুরাগী all at once?

no, not that i know of

No. And what makes আপনি think all your অনুরাগী will WANT spam messages like that?

If আপনি want people to যোগদান a spot আপনি made, বিজ্ঞাপন it. If আপনি want to greet people, just do it on your দেওয়াল and hope that people like আপনি enough to come check out your দেওয়াল periodically.