Click the floating sword icon and another icon will come up. This icon says "attack." A timer will start. Click the attack icon as many times as you can within the time limit. The character will then proceed to damage the enemy the amount of times you clicked. (Note: There is a 5-click limit currently because the characters are supposed to be weak, such as the beginning of a game)
Credit to Scratch Team for sprites, I simply modified them. This is for an upcoming game I am creating. Graphics are not final.