Arenas Selection
You will notice tabs across the top of the list. Select the appropriate tab for where you want to go.
For example, if you are playing for free, you would select the "Free" tab to get a list of free arenas, or to start your own arena. All other tabs contain arenas requiring a subscription after your two week free trial expires. The "Free" arena list is always free.
Once you have settled on a list, simply double-click the arena to enter. If you do not have a game ID, you will be prompted to enter one. If your game installation is lacking any content needed for that arena, it will be downloaded and installed for you, before putting you into the tower, of a field, in the arena.