Top Lashes: Look into a mirror and place the teeth of the comb under your upper lashes at the roots. Then blink down onto the comb. Keeping the lashes against the comb, lift the comb upward through the lash hairs to the tips.
Bottom Lashes: Look into a mirror and place the teeth of the comb under your lash roots facing upward. Gently roll the comb away from you. This will move the comb through the lashes to the tip.