Changing your headlight bulbs is one of the easier DIY-automotive jobs that people can do.  Older cars used to have a fully enclosed lamp that was specifically fitted to each individual car, with some cross-compatibility.  Most cars now have a fully enclosed "lens" and when the headlamp goes out, all you have to do is change the bulb that plugs into it.  Some are easier to reach than others, but most can be done by the average person with just a little guidance.  

What you'll need: Make sure to use gloves of some sort as oils from your hands/skin will cause the bulbs to fail more quickly due to the super-heating that happens when the bulbs are lit.  A soft cloth can also be used, but be sure not to touch the glass part of the bulb. You will also likely need a flathead screwdriver to pry the clip on the bulb connector.  Finally, finding the right bulb - both fitment and compatibility, as well as color/temperature, are important. 

Changing the Bulb: Most modern car headlight bulbs, once located, can be easily removed by grabbing the back of the bulb connector, twisting left to unlock, then carefully pulling back to remove the bulb from the headlight lens port. Disconnect from the wiring connector (usually using a small flathead screwdriver).  Then, simply clip in the new bulb -remember to never touch the glass part of the bulb with your bare hands, twist (usually to the right) back in until it clicks into place. 

Bulb Sizes/Types: Bulb sizes and fitment are usually expressed in terms such as; The most common headlight models are 9004, 9005, 9006, 9007, H1, and H4, although there are other models. Refer to your vehicle owner's manual for the proper bulb model and there are several other resources on the internet for finding this information as well. When searching on eBay Motors, most sellers will also index by Year/Make/Model of the vehicle, so searching for " 07 Acura MDX headlight bulb" should also work. 

Kelvin - Color, Temperature Scale: Example - HID Xenon 3000K, 5000K, 6000K, 8000K, 10000K, 12000K, 15000K are Light Color Codes that indicate the color of the light output. 3000K - 5000K is almost a pure white light, while 8000K  is more to the blue part of the light spectrum, and 15000K is an almost purple color of light.