The ballot is here: http://sasquan.org/hugo-awards/voting/
If you have not voted the Hugo Awards before, please note that it is an "Australian ballot," a preferential system whereby one ranks the nominees. You don't just vote for one. You can rank NO AWARD as if it were any other finalist; ahead of some nominees, behind others.
(Which is the way I believe one should use NO AWARD. As I have stated previously, I am opposed to the nuclear option of just blindly voting NO AWARD in every category).
Of course, you need to member to vote. Supporting Memberships will cost you $40. You can sign up to buy one at https://sasquan.swoc.us/sasquan/reg.php
In addition to voting privileges, a Supporting Membership will get you the convention's program book (usually a handsome item, though it varies from year to year) and other publications.