Use a stud finder to locate the studs in the wall. Mark them with a pencil so that you know where they are located.
Measure out the space on the wall where you want to create the opening. Try to select a location between studs. Mark it with a pencil, using a level to ensure that you are marking level lines. Try to refrain from selecting a location near the kitchen sink or refrigerator as there will likely be plumbing in the wall.
Lay drop cloths on the floor to protect it before you start work. Disconnect power to the area by flipping the appropriate breakers in the household breaker box. The breakers should be labeled so that you know which ones go to the kitchen and living room area.
Cut through the drywall along your measured out line with a utility knife or hand saw. Wires can be behind the wall, so cut cautiously. Use the claw end of a hammer to help break away the wall, but be careful not to damage the areas of the drywall that will remain up.
Move any exposed wires by pushing them into an area of the wall that will remain up when you are finished.
Saw through the center of wall studs that are where you want the opening to be in the wall. Once you have cut them with the reciprocating saw, pull and twist to remove.
Construct the frame for the new opening. Place two stacked 1-inch thick boards at the top of the opening for the header and secure with nails. Place a single board along the bottom for the footer and secure with nails. Put a single board along each side and secure with nails to complete the opening frame.
Repair any damaged remaining drywall by applying some drywall plaster with a knife. Once it dries according to the manufacturer’s directions, you can smooth it with a sanding block. Paint it as needed to match the rest of the wall.