My current ceiling fixture has 6 wires. 2 red, 2 black and 2 white. The new chandelier has only 2 wires. Which wires do I attach the new chandelier to?

The easiest method is to not what two wires the current fixture is connected to, Take a picture to make sure.

Then connect the new fixture in the same way. Do not take anything more apart then is absolutely necessary and make sure the power is off when working on the circuit.

By "ceiling fixture" do you mean ceiling box?