A Buy order will only be completed when another user creates a sell order in the same amount and price set by you, until then your buy order will continue to wait until a price is matched. If you wish to make quicker trade, you should examine the order books that displays the prices of the last orders carried out by different users. This way you can determine the best prices for your buy orders.
Click on the "My Open Orders" tab to see the order you entered. Click on the "My Trade History" tab to see your orders in the past.
For more information about Buy/Sell orders, read our help article.