Make a ki ball. Then visualize the ball turning into a redhot flame. Pretty simple really.
Make a ki ball and change it into a fireball. Then shoot it off like you would a ki blast. Remember to yell loudly when doing this.
Make a fire ball and shoot it at someone. Visualize the flame engulfing the body. Visualize it burning theres entire body. In the words of ki trainee, "It doesnt cause physical burns but it hurts like a ho." lol.
Move a lot of ki into your index and middle fingers, and then clench your fist like you would to punch someone. Then make the ki in your fingers turn into flame. Then(obviously)punch someone.