Avid Elixir Compatible Disc Brake Pads

1 pair of brake pads
1 spring
metal pin not included

You should try braking quickly a few times on a dry, flat, obstacle-free surface. 3 or 4 sets of 10 dry, intermittent stops are enough to break in your pads. Dry braking will wear down the pad a bit.
Release your brakes for a few dozen seconds between each set of stops in order to let them decrease in temperature before starting a new series of 10.

If you brake continuously or not enough, this can glaze your brake pads. Rather than slightly crumbling, the brake pads melt. This will leave a thin layer of melted silica and metal on the top of your brake pad, making it less effective.
If this happens, don't throw away your brake pads as they can still be revived. A few short, sharp squeezes of the brakes should wear the glazed layer and make your brakes work again

If the problem persists despite several short, dry stops, lightly rub your brake pads with sandpaper.