Two ways to do it. Take down the old light and install a plug there. Or better yet take the old light down and wire the new one in its place. All you would have to do is cut the plug off. Strip some of the insulation off the wire and wire nut it to t...
Check out the free tutorials at this site. Not only do they discuss very inexpensive lighting, they also show some basic lighting setups.
Hacienda Lighting and Aztec lighting are two of the bigger lighting companies in town. They do the majority of the work for home builders.