Access the Troop Upgrading System by repairing the new statue available within your City:

This First statue contains access to the first available troops for upgrade, the Minotaur and Longbowmen. You will gain access to the Minotaur shortly after accessing the statue (if you meet the requirements for training Minotaurs), and will receive your first unlocking item (Mauve Mist Key).

The Second Statue contains access to the next 2 troops, Swift Strike Dragons and Battle Dragons and requiring a Sun Glow Key.

Gaining access to subsequent troops will follow a similar pattern, requiring the player meets the requirements for training the troop as well as an unlocking item.

More Information on Acquiring Troop Upgrading and Unlocking items --- HERE

Troop Upgrade Levels
All Troops begin at Level "0", and can be upgraded to increase their power. These upgrades will apply not only to newly trained units, but will be applied retroactively to your standing Army! Currently the Level Cap per Troop for the Upgrading system is Level 15.

Stats Increase Display
By Clicking and dragging on the arrow towards the bottom of the screen pictured below, you can view the current stats of the selected troop and future stats that can be had with successful upgrades:

More Information on Upgrading your Troops can be found --- HERE