The only one who can answer this is a recruiter. There armed forces only need a certain number of “qualified” candidates each year. Your task is to be the best qualified individual to come into their office. BE PREPARED.
Go to navy.com and search careers. Enter construction and you will see a list of specialists.
If you not quite ready or eligible to enter the service, find a job with a local contractor. Sweep the floors, take out the trash, dig ditches, or whatever they need done. This will show the recruiter you are planning ahead.
Stay in school. Work hard and make good grades. Put in extra study time. Do any extra credit assignments you can. This will show the recruiter you mean business.