1st your age can be an issue; if your a “minor” you likely will have to have parental consent.
As for what to do at Mass:
1 stay to the rear pews until you get comfortable. It’s easier to follow the actions that way
2 MOST churches have a book or booklet that tou can use to read and follow along: if not
If you have a SMART PHONE download
www.Lawdate.com & go to “Order of the Mass”
Here is another thing you can print off
Mass Responses and Prayers
The Roman Missal, Third Edition
http://www.catholictv.com/mass-prayers-responses
I’ll be happy to answer any questions you may have. Send me a private message
Also as a FYI
Most often RCIA runs from Back to school to Easter Sunday, so you should act quickly on this; CALL the Parish Office for more information and ask what you need to do.
God Bless you
Paay much my friend,
Patrick