I missed the first day of middle school?

I missed the 2nd year of middle school first's day. I am in 7th grade and I am so confused on what I actually do when I get to the school on the 2nd day..do I go to the office or do I go straight to homeroom???? I am not worried about the first day at all and I dont care that I missed it..I just dont know what to do when I get to the school on the 2nd day. What will the new teachers think of me?? What will they do?? Will I have to go to the main office to get my locker combo and how do I know where my new teachers are..Since it is the 2nd year of middle school I know all the students so thats a big plus...But like what will I do.. PLEASE HELP!