Your main occupation is going to and completing HS.

so..."HS Student"

___________________________

Make sure you indicate that you can be claimed as a dependent by someone else in the "My Info"  section where you edit your name.  Miss that and you will severely PO your parents...and create a filing mess for you and your family.  Don't rush to file, and print out your forms and have your parent(s) review them before you file. 

If your are your parent's dependent, I recommend entering the occupation, STUDENT DEPENDENT.

The IRS couldn't care less what you put for occupation - so long as you pay your taxes. Here's an example of a few "occupations" I've seen on filed and accepted tax returns over the years, and the IRS didn't so much as bat an eyelash.

Occupation                       Real Job

Mass Murderer           Pest Exterminator

Human Trafficker       Modeling Agent

Serial Killer                  Pest Exterminator

Drug Dealer                Pharmacy Technician

Car Jacker                  Worked for an automobile repossession company

Hijacker                       Aircraft Reposessor

Money Launderer        This guy worked at the U.S. Mint. His job was to wash newly minted coins.

Terrorist Eradicator     Navy Seal (I'm guessing he was on seal team six - but they won't say)

Computer Hacker       Guy worked for the CIA – nuff said.

Overall, the IRS could really care less how you get your money - so long as you pay your taxes on it.