I want to join the Tennis team?

I am going to a new school and I will be a Junior. I have no extracurricular activities and I really like Tennis. I did it in 9th grade for a little bit but had no support and real racket so quit. This time I will take it more serious. This summer I am trying to get in shape. If I dont know how to play will they teach me? Is it too late for me? I only have ONE month left to get in shape and I have been slacking this month. What exercises would help