Because the election is administered by the Westercon two years before the target year, the address to which you submit your bid changes every year. This year being 2015, the election is for 2017, and would-be bidders file with the 2015 Westercon in San Diego. If you want to bid for 2018, you file your papers with the 2016 Westercon in Portland. There's no single fixed address, no online form on a single web site, and no single point of contact, and this apparently is confusing to people coming to Westercon out of the blue. Worldcon is the same way, which is presumably why sometimes the Worldcon web site gets e-mail from groups who want to know how they can persuade the WSFS Board of Directors to award a Worldcon to their city.
Anyway, in light of the request for clarification, I wrote an article for the Westercon web site entitled How to Bid for a Westercon. I hope it helps. I'm so close to the process that I clearly cannot see what things newcommers cannot see, so I'm likely to not be fully explaining everything you have to do.