Happy Birthday!
The Loc 4.0" Goblin or the Apogee Zephyr are both good choices. Look on the Loc and Apogee sites and watch the videos on how to assemble the rockets. This will give you an idea of what is involved in building the rocket.
Check the NAR.org website https://www.nar.org/content.aspx?page_id=22&club_id=114127&module_id=668315
Check the section titled HPR Level 1 Certification. There is a wealth of knowledge and the answers to many questions you will have.
Use Open Rocket to help select a motor. Thrust to weight ration should be 5 to 1. Speed off the rail should be 35-40 MPH. Chute deployment speed should be no more than 30 MPH. Your certification team will ask you about projected altitude, center of pressure, center of gravity, and questions about how you built the rocket.
Don't be in a hurry. You should get some experience flying mid power rockets. You should fly your level 1 rocket on a G motor as a test flight. It's nice to see people your age interested in model rocketry. Hopefully we can get you off to a good start.
Feel free to attend a CMASS Zoom meeting. You can send an email to officers@cmass.org for meeting information. Meetings are a great opportunity to get answers to questions.