That's what I had to do years back when one of my laptop's wifi quit working. The slide in radio was MUCH cheaper than getting it repaired...but back then it was the size of a credit card and not usb...and plugged into the now extinct PCMIA slot (or something like that)
Most if not all computers have a small wifi signal indicator in the bottom right corner.
The one in the center with bars.
Clicking on this should give you a pop-up that lists the wi-fi networks in range. If you don't see this symbol, somethings wrong with your wi-fi adapter. If it's crossed out, your adapter is turned off.
They can be turned off with a small slide switch somewhere on the outside of the laptop or using a combination of the Function (Fn) button and a Function key like F5.