Your regular teacher can not be in the classroom every day. There are times that she will get sick, have meetings to attend, or have other things to do that will keep her away from class. When your teacher can not be there, the school will hire a substitute teacher to teach the class in her absence.
Enter the classroom quietly and sit in your assigned seat if you have one. Answer to your name when he takes attendance.
Show the substitute teacher the same respect that you show your regular teacher. Do not be rude or disruptive while she is teaching the class. If your peers goof off and treat the subsitute disrespectfully, refuse to join in.
Understand that everything is new for the substitute. He probably doesn't know the class routine. He is not your regular teacher and might not do everything exactly the same as your regular teacher. Just because his style or methods are different does not mean they are wrong. Help the substitute teacher to learn the class routines and schedules if she asks for your help.
Cooperate with the substitute teacher and do what he asks you to if it is reasonable. If he makes unreasonable requests, discuss the problem with another teacher.
Follow instructions of the substitute teacher and do all the work that she asks you to do.
Behave the way your regular teacher would expect you to behave. The substitute teacher will report back to your regular teacher to let him know how the class behaved.