Check your motherboard manual. Close to the front, you will see a drawing of your motherboard. You will see several little 9 pin blocks labeled USB. Each one of those blocks has pins for 2 USB ports.
If you do not have enough front panel connectors, you can buy USB connectors that fit into case drive bays, something like this:http://www.newegg.com/Product/Product.aspx?Item=N82E16820132020
You can also buy similar expansions with just 4 USB ports.