Summarize:

Although whitening toothpastes will not dramatically improve the whiteness of your teeth in the space of an hour (they are more effective over time), they can still help to remove stains and make teeth look brighter. Whitening toothpastes contain abrasive particles which polish the teeth and wear away stains (without damaging tooth enamel). They also contain chemicals (such as blue covarine) which bind to the surface of the teeth, making them appear whiter. To use whitening toothpaste, place a pea-sized amount on your toothbrush, and brush using small circular motions, holding the toothpaste at a 45 degree angle from the gums. Whitening strips are coated with peroxide gel, which bleaches the teeth and helps them to look whiter. You will typically use two sets of strips per day, for 30 minutes each -- giving you a whiter smile in only 60 minutes! Whitening strips can be purchased over-the-counter at the drugstore or supermarket. Avoid purchasing a brand that contains the ingredient "chlorine dioxide" as this can damage the enamel on teeth. To use the strips, remove them from the package and apply one strip to your top teeth and one to your bottom teeth. Leave them on for 30 minutes. Some strips will dissolve by themselves after use, while others will need to be removed. For best results, continue to use the whitening strips twice a day over a two week period. Like the whitening strips, whitening pens use a gel containing peroxide in order to bleach the teeth. To use, remove the cap and twist the pen to release the gel. Stand in front of a mirror and smile widely, then use the pen to "paint" the gel onto your teeth. Keep your mouth open for about 30 seconds to allow the gel to dry. Try not to eat or drink anything for 45 minutes following the treatment. For best results, repeat this process three times a day for up to a month. A whitening tray is another great option for quickly whitening your teeth. They can be purchased over-the-counter or can be custom-made by your dentist. To use a whitening tray, squirt a small amount of the concentrated peroxide gel provided into the tray (which looks like a plastic retainer) and fit it over your teeth. Depending on the type of tray, you may only need to wear it for half an hour, or you may have to leave it on overnight. Although a single use will leave your teeth looking brighter, if you want significantly whiter teeth you will need to use the tray multiple times. Although custom-made trays from your dentist can be pricey (usually costing around $300), they are specially molded for your teeth, making the treatment more effective than store-bought "one size fits all" trays.
Use whitening toothpaste. Use whitening strips. Use a whitening pen. Use a whitening tray.