Head down the mountain path, and SAVE! You get to fight your first Gear battle!
Musha Mk100 x 2
This isn't a hard battle since it's an introduction to Gear fights. Like regular battles, you can use , , and attacks, costing 10, 20 and 30 fuel respectively. You only get one attack per turn, though. You start with 1200 fuel, and you can use the Charge command to recharge 30 fuel. You can also turn on Booster for a Haste-like effect which drains a percentage of fuel every turn.
You have 1800 HP in your Gear, and they do about 80 damage per attack. Just use attacks until they die; should take 4 total. Booster is not necessary.
Watch the scenes.