Answer:
If you mean the one with the train thing, you use the first two red to kill the two pigs that are closest to you, the first one takes out the wooden pole, and tries to kill the mustached one. The second red one goes through the ice and kills the second pig hiding there. You use the yellow bird by shooting it in the air at a very high angle, so that if you didn't tap it, it would land around the area that the second pig is hiding. You need to practice this a bit, but you make it go fast so that it will go straight through the wooden block on the side of the car that's holding all the dynamite. If you aimed it right, it will blow the whole car up and kill the last pig. If you do it right, you should have a red bird left over, and you should get three stars.