Before talking about the installation for a hid lights on your car, we better talk about what's included in a HID conversion Kits. There are 4 common hid kits on the market.
Single Beam Conversion Kits -- H1, H3, H4-1, H7, 9004-1, 9005, 9006, 9007-1, with 2 ballasts and installation clamps.
Hi-lo Beam : H4-2, 9004-2. 9007-2 hid for low beam and halogen bulb for high beam, with 2 ballasts and installation clamps.
Telescope Kit : H4-3, 9004-3, 9007-3, single HID can switch between high beam and low beam, with 2 ballasts and installation clamps.
Bi-xenon Kit : H4-4, 9004-4, 9007-4, 2 HID bulbs on each bulb, which works for high and low beam, with 4 ballasts and installation clamps.

These kits are designed to produce more light and last longer than any other lighting kits out there. HID kits are a complete replacement to your existing headlight bulb, yet they are extremely easy to install. That starter takes the signal from the vehicle and quickly sends it to the ballast. The ballast then amplifies the signal to a high current signal and sends it to the bulb. The plug in HID bulb receives the signal and creates the light. The bulb is filled with a mixture of gases and salts. When the bulb receives the amplified power from the ballast, it energizes the gases in the bulb creating a white/blue light output. The color varies, depending on the Kelvin (K)/color temperature of the kit.

We like these kits because of the functionality and visual appeal they offer. The really do add class to your car, as well as give you a little bit more confidence behind the wheel in less than perfect conditions such as fog, rain, or night time driving. These kits are easy to install. First, layout the components and find a good mounting spot for both the ballast and starter. Be sure the wiring from the both of them, including the bulb, reach without being too snug. Once you find a mounting spot, mount them securely into place. Be sure to fasten them well to the vehicle. Now, remove the stock halogen bulb from the headlight housing using latex gloves and unplug the plug from it. Now take that plug and plug it into the starter you just mounted. Plug the starter into the ballast, then carefully plug the new bulb into the headlight housing. Use latex gloves to do this because you don't want to touch the bulbs with your fingers. It should go in the same way the old one came out. Once it is securely fastened into place with all rubber garments reconnected, plug the ballast into the bulb. You may find that you need to adjust the headlights. You can find information on how to do this by checking your owners manual.

And the price for a full kit of HID lights, it's getting cheaper and cheaper, it's around USD 109 shipped, and most vendor offer 1 year warranty for your kits. So it's not a bad idea to upgrade your halogen bulbs to HID bulbs. Please make sure that you know what kits you need to install your hid light