Sorry, there are currently no openings for any wiki staff members at the moment. But even if there were, admins aren't selected simply by application: they're personally (by me, so far) hand-picked from the community.
The precise selection process isn't exactly detailed anywhere, but I typically look for users who display certain traits suitable for running a group of people: natural leadership, maturity, logical thinking, etc. And on top of that, you have to be an active user on the wiki for quite a while - Zaralith was active for three years before I asked him to be an admin. It doesn't necessarily have to be that long, but at least long enough that I know that the user knows how things work around here. Perhaps a minimum of 6 months?
Anyway, sorry, we don't appoint staff (especially admins) the same way some other wikis do. They're all very important roles that are only entrusted to active, mature users.