First, you need to know not only the candidates, but also the multiple constitutional amendments being forwarded this year. It's the constitutional amendments that most often get shafted when it comes to coverage, but the Idaho Voters Pamphlet put out by the Idaho Secretary of State's Office is a handy little primer. If you can't find the copy that was mailed to you, you can download it online.
You can also download a copy of the full candidate list for all statewide offices.
Second, you need to know where to vote. If you're not sure of where your polling place is, the Ada County Clerk's Office is ready to help.
Third, once you get to your polling place, you'd better have you photo ID—you'll need it in order to vote thanks to a recent change in the law.
Fourth, make sure to give yourself some time: The ballot is four pages long.
Finally, if you're wondering if it's all too much hassle, remember, that if you don't vote, you don't get to complain.