Type in which card you want to select. Type in "No" when you have more cards to select once the game asks you to move on to the battle phase. Type in "Yes" for when you want to move on. The Battle Phase is a little weird: The battles don't take into account the ATK of the other Battler, just their HP.
Here's a helpful guide to the game! :) Scout: 1/1; 1 Cost Soldier: 2/2; 2 Cost Healer: 1/2; 2 Cost. SPECIAL: Adds One HP to your Current HP. Bomb: 0/0; 3 Cost. SPECIAL: Destroys the Opposing Card. Training: 0/0; 3 Cost. SPECIAL: Gives your Card +1/1. C-Goat: 3/2; 4 Cost. SPECIAL: Deletes a Card from the Opponent's Hand. Virus: 0/0; 5 Cost. SPECIAL: Deals -2 Damage to the Opposing Player. Reload: 0/0; 3 Cost. SPECIAL: Deletes your Hand and gives you Two New Cards.