How Do You survive in a high school where you dont know anyone?

okay so i am moving to a new town and i have to go to a new high school(ill be starting the 9th grade in September) the problem is i dont no anyone! i have gone to catholic school all my life soo i have no idea what to expect! how do i make friends? where do i sit at lunch! im asking for a general run through of what i need to do to make friends and become known. i can handle the work its no problem.ewww and do i have to get changed in front of the other girls at gym?? just pleasee give me a step by step plan of what i need to do thank you!!