But I don't know how to play it. There is a way to test it but I don't know if you can play it with people yet. Anyone know if you can?

http://forums.sc2mapster.com/development/map-development/344-play-custom-maps-on-official-battle-net-custom-games/ that's with the official beta. All people playing must have the map.

Get my key on 28th, heading straight to the map editor!

I can't play my map
"Unable to open Map"

I've 2 players and both have start locations.

Can you test your maps?

http://www.sc2mapster.com/maps/team-micro-arena/
How am I supposed to play this without having to find 3 people to do that little trick to play on B.net?

Make sure you aren't using the "Campaign" dependencies in your map, we don't have the Mod Campaign data.