An ethernet cord can connect two machines using the ethernet ports on each. A small plastic piece on the end of the cord, called a modular plug, helps lock the cord in place. The cords are commonly used to hook a computer to an Internet modem. Plugging in an ethernet cord takes two things--care and patience, because the small plastic component on the modular plug can easily break if handled too roughly.
Hold the cord firmly in your hand and turn it so the small plastic component that looks like a flap on the modular plug is facing up.
Insert the modular plug into your computer's ethernet port. A computer has several ports for different cords, including a USB port and a telephone cable port. The ethernet port is slightly larger than the telephone cable port.
Firmly push the modular plug into the ethernet port making sure the plug locks into place. You should hear a low snapping sound.