Make sure you take down the measurements of your skirting boards accurately. Remember the rule of thumb, measure twice, cut once. Use the tape measure to work out the lengths you need your skirting boards to be. Transfer this distance onto the skirting boards. Use the handsaw to draw a straight line across the skirting board.
After you have marked up the skirting board, use the miter box and handsaw to cut it at a 45 degree angle. This first piece of skirting that will be cut to match the profile of the board.
Measure the length of the wall for the first skirting board. Then cut the board to length with a 90 degree cut at both ends. Use a stud finder to locate the wooden frames behind the wall. Attach the skirting board to the wall with the nail gun to, so that it is flush to the corner. Cut the skirting board with the scribed joint to size, then push it against the first skirting board so that it's flush. The secure it using the nail gun. Repeat the process until all the skirting boards are installed.