The two most important committees in the House Ways and Means Committee because it is the one that writes bills about taxes. (Remember-money is always the most important thing!)
The House of Rules Committee is also very important. It controls the schedule and rules for how amendments are heard. (An amendment is a change to a law).
They decide what amendments can be looked at, when the House can bring it up to discuss, and how much debate will be allowed (can the Reps give long speeches or just have 5 minutes to argue). All of these powers decide which amendments the House will vote on and which laws can be changed.