Every refrigerator is different, so you will likely have to adjust these instructions to suit your own refrigerator, but not much. Most basic and mid-range refrigerators are illuminated with a single standard light bulb at the top. You'll be using the power source for this light bulb to illuminate your LED tape. Using this source will also turn it on and off.

Originally, I thought to remove the bulb and use a lamp socket power adaptor, which would be the fastest and simplest way to power your LED tape. Rather, I opted to keep the existing lamp and tap into it's wiring. The LED tape will require a low voltage transformer, commonly 12V DC. These are often very small for this purpose. They can usually be purchased from the same source as the LED tape. I happened to have an acceptable transformer on hand. Be sure to use a DC transformer to avoid flicker. The smaller the transformer the better as you will want it take up the least amount of space in your refrigerator. You may also get lucky as I did, and be able to secure the transformer inside a plastic panel that housed the wiring for the existing lamp and also had a reasonable amount of room to spare. Otherwise, I'd suggest using some zip ties and your imagination to locate the safest and most out of the way location.

The warm white LED tape I used was not water proof. While most LED lighting I saw in refrigerators was a very cool-white color and gave the empty fridge a modern aesthetic, the blue-white color temperature doesn't make food appear as much appetizing as it does sterilized. Take a look at the super-warm color temperature of lighting used in the produce section of groceries. I would recommend using a water resistant model of LED tape to avoid damage and prevent hurting yourself on the sharper edges of raised LED's, which are sealed and prevents minor injury from scraping your hand. That said, it's been a couple years, and I have experienced no problems whatsoever with the unsealed LED tape I've used.

Here are Amazon links for LED tape options a transformer, and optional socket adaptors:

Silicone sleeve enclosure LED tape: http://amzn.com/B00CMX2KGK

Epoxy enclosure LED tape: http://amzn.com/B006079BCK

12V DC transformer: http://amzn.com/B007ME2HMQ

Plug-free 12V DC transformer: https://amzn.com/B017R17YQC

Lamp socket adaptor: http://amzn.com/B001PCVTFC

Lamp socket that permits continued use of existing bulb: http://amzn.com/B0015SJYRQ