Look for the USB Adapters... Of course there are other brands, but now you know what you are looking for...
A USB Adapter is the easiest way to go, but if you are not scared to install a card into the computer, look for a PCI or PCI-E Wireless Adapter. Some Newer Computers don't have a PCI Slot as most are trying to go to PCI-E... In which case if you don't know, contact your Manufacture of the Computer to find out the Specs on that.
Good Luck and all of which is very easy to do it yourself. No need to hire a tech to do it for you.