Only last season or this season paid full members are allowed to vote.
If there is only one person running for an office you can elect to nominate a person of your choice. Simply select 'other' and 'write in' a name. You will be asked for your name before you can submit your vote. This is only to verify that you are eligible to vote and that you don't get counted 2x. The outgoing President will be the only person to see this information.