How do I improve my might and gain more troops?

Training troops is simple. You have 4 troop training buildings, Shooter Camp, Fighter Camp, Rider Camp and Vehicle Depot. Just train as much as you can here. Upgrade those buildings to get higher tier troops and upgrade the bootcamp buildings to let you train more troops at one time.

Training will raise your might. You also gain might from upgrading buildings. completing research, improving your heroes and increasing the commander stats through Gear, Chips, Modules and Cubes.