If your motherboard has not got USB2 built in you can get an add in card to use USB2.
I am not sure if you can get extensions from the cards to go to your from USB ports. Someone else might know different.
If not it is a case of plug the card in and load the drivers. This will give you 4-5 more USB2 ports.
If you need more than that you can also get USB2 hubs to increase the number or ports required.