Start off by making a hole in the crotch section of your pants, make it big enough so your head can fit through it. Then simply put your head through the hole you just made, arms through the trunks.
Then put your right/left leg through the left/right sleeve respectively. Maybe get a clip or something to clip it to your boxers or w/e you wear so it doesnt fall down.
The neck section is for easy access when you need to go to the toilet.
Put your white shoes on just as if they are gloves.
Now go try it on, you promised.