From your private message to me, you indicate that someone has told you that your computer has built-in wifi. I never said that, and the computers that do come equipped with wifi use a special mini-card for that purpose. So far as I can tell, your computer does not have a slot for such a card.
If you take a look at the earlier messages in this thread, you will see that you have at least one alternative wireless option. It is possible to purchase a USB wireless adapter that simply plugs in to an available USB port. If you insist on an internal card, however, you must find a vendor who will provide a low-profile bracket for their PCI-e wireless card.
EDIT: Your computer does have a built-in Ethernet port on the rear panel. If your Internet provider has given you a device that has an Ethernet port, you can attach an appropriate cable from that port to the port on the rear panel of your computer.