Cut the holes for the pegs inside, the pegs outside, and the mountain shape outside the line. You can optionally engrave the 'snow limit' lines, and paint the tops of the mountains.
The holes (or the pegs) will obviously need some manual work to fit, best is to slightly file / cut the corners of the holes, till the pegs hammer in easily.
2 wood screws hold this firmly on your door or wall.
Enjoy!