The correct answer is that it depends on the laws of the state in which you permanently reside. Google for the Secretary of State of your state, and I'm certain that registration procedures will be readily available.
I do know that 17 year olds are permitted to vote in Ohio Primary elections, provided that the elector will be 18 years old on or before the date of the November General election of the same year. In order to vote in any election in Ohio, you must be registered in the county in which you reside; failing that, you may cast a provisional ballot in your county and precinct of residence, provided that you are registered in any county in the State of Ohio.
So, which state are you in?