can you post a pic of the chandelier that you want installed?
also post a picture of where the chandelier is supposed to be installed.
theoretically speaking if box is already in the ceiling and its not something complicated like one of these:
and is instead something simple like a one piece chandelier that doesnt require hanging/arranging all the crystals it shouldnt be too bad of a job.
locate the breaker panel in your home and look for the one labelled for the room in which the chandelier is located.
turn the light on for your existing chandelier and have someone stand in the room. shut off the circuit breaker and confirm that the chandelier is not getting any power/electricity (this will be evident when the light goes out in the chandelier even though the light switch is in the "on" position).
put the switch for the chandelier to the "off" position and climb on up with a ladder. the chandelier is "usually" held in with two screws although without seeing any pictures i cant say for certain. sometimes there is a central screw and hook that holds a chain for the chandelier i believe.
remove the screws for the existing chandelier.
there will usually be 3 wires. there is a black wire which is hot, white which is neutral/return and a copper wire connected to a green ground screw.
the wires are usually twisted together and connected using something called a "marette". it will be screwed on so turn the marette counter clock wise to remove it (lefty loosey).
once removed carefully pull the wires apart and remove the chandelier.
inspect the wiring. the wiring coming from the breaker panel will be solid while the wire from the chandelier is usually stranded.
take the new chandelier and connect the wires. the chandeliers will usually come with matching colors. the wires from the chandelier should come with about a 1/4" pre-stripped so twist the stranded wire together until its solid. twist the matching colored wires together (so black to black and white to white, copper wire to green ground screw). twist on a marette clock rise (righty tighty) onto the black (hot) wires and onto the white (neutral/return) wires and then tuck them into the junction box.
attach the chandelier to the junction box with the included hardware.
make sure the light switch is in the "off" position still and go back to your breaker panel and turn the circuit breaker back to on.
head back to the room with the chandelier and turn the light switch for the chandelier to the "on" position.
if you have done everything correctly the chandelier should light up. if you run into any problems refer to the instructions that came with the chandelier (which you should read through before starting this) and check to see if you missed something.
I have to stress that electrical work
CAN be dangerous. If you dont feel confident doing it I suggest forking over whatever an electrician charges. Since matlock's an electrician and an RS member maybe you can get him to do it and help support the RS community.