Bids open every 2.4 hours. Alice and Bob both bid for in the same voting batch. If Alice bids 4 SBD and Bob bids 2 SBD, Alice will get a 66.66% upvote and Bob will get a 33.33% upvote.
You need to transfer minimum 0.1 STEEM or SBD (If you don't have so much, use @iprofit). You will get vote when bot reach 100% voting power. You can see voting power at SteemBlockExplorer.
Minimum bid is 0.1 SBD/STEEM. If you send less, you will get refund.
Maximum bid is 1000 SBD/STEEM. If you send more, you will get refund.
Minimum post age is 15 minutes. If post age is less than 15 minutes, you will get refund.
Maximum post age is 84 hours (3.5 days). If you post is older, you will get refund.