It comes as a tin of gooey paint and a tub of powder. You really need the applicator, too, which is a simple cardboard pump like an old-fashioned balloon pump.
Make a sort of tent with a cardboard box inside a big plastic bag, paint on the gooey paint, put it in the tent and spray on the flocking. Or pour in the floking, put lid on your box and shake it about. Tip out the excess and leave it to dry. You can then recycle all the excess powder.
It's a good idea to buy a separate pump for each colour you use, though. You only need one stray speck of the wrong colour to ruin your work.