The state of New Hampshire has a vaccine rollout plan with three different phases. That plan is shown in the infographic below from https://www.vaccines.nh.gov/vaccine-phases:
As of Friday, April 2nd, any individual age sixteen or older became eligible to get a COVID-19 vaccine. There is no vaccination option yet for those under the age of 16, but there are clinical trials occurring for children between the ages of twelve and fifteen. In fact, the Phase 3 Pfizer-BioNTech COVID-19 vaccine study has shown a 100% effectiveness rate for those between twelve and fifteen years of age according to Pfizer Inc.
People who are eligible and willing to get vaccinated in New Hampshire should register as soon as possible at https://www.vaccines.nh.gov/ using any computer, smartphone, tablet, etc. The website will take you through a few steps including creating an account and selecting a vaccination date and location. It is a very hassle-free process that can be completed in under fifteen minutes.