It looks like your motherboard has two PCI slots and one PCI-e x16 slot. Your best bet is to look for a PCI based add-in wireless adapter.
Here is a list wireless adapter add-in boards, that are PCI based, you can browse:
http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&N=100010074%20600014290&IsNodeId=1&bop=And&Order=PRICE&PageSize=100