Place a tape measure below the top of the door frame and measure the width of the door frame. The measurement is the length needed for the curtain pole.
Purchase inside-mount sockets to hold the curtain pole. Sockets come in different sizes and the pole must be able to fit inside the socket. One package contains a left and right socket, and screws.
Position the socket on the inside of the door frame, 1 inch from the top of the door frame -- this clearance below the top of the frame allows enough room to put the curtain pole into the socket. Use a pencil to mark the placement of the screw onto the inside door frame. Place the pencil lead through the screw hole in the socket and mark the frame. Repeat this method to mark the placement of the second socket.
Use a hammer and nail to create a starter hole for the screw. Pound a nail ¼ inch into the wall and remove the nail. The hole makes it easier to drill the screw.
Hold one socket against the frame and match the hole in the socket with the starter hole. Use a cordless screwdriver to drive the screw and attach the socket. Attach the second socket using this method.
Place the curtain onto the pole and place the pole into the sockets.