This is mostly for new players that want to join our community as Kotoba Miners still uses version 1.7.9 or 1.7.10, (as of Nov 17th 2014). You will be denied connection if you run anything higher. This tutorial applies to both Windows and Mac OSX since they both use the same launcher.
On the bottom left where you pick your profile, you should see something similar to what I have. Just press “New Profile.”
You should be presented with a very similar window to this.
This can be changed to whatever you want, preferably to something like “Minecraft 1.7.10” for easy identification.
On the “Use version” drop down menu, this is where you have to change to 1.7.10, so just look for “release 1.7.10” and pick it.
Then on the Minecraft launcher, on the lower left corner drop down menu select the profile you just created and launch the game.
If you see “Minecraft 1.7.10” on the lower left corner, then everything is OK!
Now you should be able to join the Kotoba Miners server!
Still stuck? Leave a comment.