I just became a Novice; Why can't I vote yet?

When you rise to the status of Level 2: Novice, you will gain the ability to vote.

Votes are allocated once a day, at 00:25 (12:25 AM) server time (EST/EDT), so you may have to wait until the next day after attaining level 2 to get your first allotment of votes.

Voting/Experience System has info on how many votes you get at this and each succeeding level.