How To Change A Plug On A Lamp. This is a standard 115V AC 15 amp plug. Then connect the new cord to the socket.

Another option is to change the current hardwired light connections to put a plug there. Once loose lift the plugs top cover to expose the wiring. Use an adapter like the below.
See the post on how to do this step for shaded lamps here.
Once loose lift the plugs top cover to expose the wiring. If your lamps plug is the closed rubbery type without any visible screws your only option is to cut it off and replace it with another plug. I mean its just two little wires right. Use an adapter like the below.

