Get up into your attic.. If there is no flooring to walk on up there get a full sheet of 4 x 8 ft. Plywood to slide around from place to place to stand on as you work if you can fit the plywood thru your attic access otherwise use pieces, etc... Local home improvement stores sell rolls of 2ft. Wide insulation.. 2 options on average to apply the insulation to the rafters so they stay in place [1] Buy a box of 1" 1/4 ROOF NAILS and get a hammer and the insulation is nailed to the inner sides of between each of the rafters using the outer lips of the insulation.. This is easily noticeable [the paper lips] once you get the insulation rolled out.. OR [2] one can use a staple gun and use staples instead of hand nails doing the same procedure.. Get a UTILITY KNIFE and measuring tape for last tools you will need and lay out the insulation and measure the length of the rafters and cut the amount of insulation you need.. Once you get going your natural instinct will govern how much insulation you want to put into sections.. Is always great to get the insulation way down into the bottom triangle section where the floor your standing on gets tied into the roof rafters at the bottom.. Is difficult area to work in obviously as you will have to get on your stomach possibly to reach down at the bottom of the rafters.. This is how it gets done.. Hope this helped out a lot.. Tony