Hahaha. So here's how the steem engine work. On the left hand side you see the price and the amount of tokens someone wants to buy and what they are willing to pay for that.
On the left the same...but for the sellers. So you either place a bid(the top bid is the highest bid) higher/lower than the top one and wait till it i filled or you can either go and match the price of one of the sellers and buy instantly.