For the first step, go to amazon.com
and buy a welding mask. It doesn't really matter which one you buy.
For this mask, I just bought the cheapest one
(I'm not going to actually weld anything). Take the headstrap out by unscrewing it.
NOTE: the kit's units (LEDs) come in threes. Drill your holes accordingly. (I just traced a template on a piece of scrap cardboard to help me measure).