Deb,
I believe that the concert that you want is part of a Beach Festival .. see <a href="http://www.festasdapraia.com/" target="_blank">http://www.festasdapraia.com/</A> ( its in Portuguese but will give you the drift ). Looks like the Moody Blues play on the Beach at Praia da Vitória on the 5th. I think that the only way to get there is via Lisbon. TAP have 3 flights a day LIS-TER (TERCEIRA AZORES). I can't see any prices for tickets but the above site has a contact email address which might have more info.
For more info on the Azores try <a href="http://www.rrtur.com/index.php" target="_blank">http://www.rrtur.com/index.php</A> or www.azorestourism.com.
There is a bit of info here and the beach in question <a href="http://www.portugaltravelguide.com/en/praia_da_vitoria.htm" target="_blank">http://www.portugaltravelguide.com/en/praia_da_vitoria.htm</A>