Have a Leviton dimmer with red, black and green wire. House wiring is black and white wire and copper wire. I assume that copper wire is ground and connects to green wire but I am not sure where the white (hot) wire should attach to (black or red) on the dimmer switch?

http://www.automanualparts.com/wiring-diagram-for-3-way-switch-with-dimmer/

use above link

Cookrobert- you have to determine wich wire is the common wire in the box (house). Look in the box and see wich two wires ore in the same sleave. (These will be your travelers, (more than likely a black and a red) the wire that is in its own sleave (black)with a white tied to other whites is the common. Now the dimmer will tell you wich wire is commom. Tie the tow commons together. The green wire is ground if your house does not have ground , cap it and forget the green, if your house does have a ground (bare copper wire) then connect the green to the bare wires is the house box. Now your to travelers on the house side will tie to the two travelers on the dimmer side. Once you have found the traveller's on the house side and dimmer travelers they can be flip flopped. It dosnt matter. Just as long as they are the traveller's it will work. It sounds complicated but I'm sure you got this. I'm a 30 year electrician. (master).. I'll be looking for your update my friend. Good luck

Connect the green dimmer wire to your ground wire

As a general rule for timers and dimmers:

The Black dimmer wire connects to black hot wire coming from breaker (122V line)
The red dimmer wire connects to Load (wire going to chandelier)

The wall red wire that is capped could be a couple different things. a) It could go to a second switch that was used to control the chandelier. b) it could be another wire that goes to same ceiling box as chandelier to be used to control a fan, except you don't have a fan. In the second case, if you install a fan with a light, you could control fan and light separately.

The green is a ground wire that connects to bare copper wire in box. The bare copper connect back to main breaker box on the Neutral busbar.
White wires that are twisted together inside your light switch box also connect back to to main breaker box on the Neutral busbar.
The ground wire and neutral are a redundant safety system to protect you from electrical devices and appliances that have 'shorted'
The black hot wire connects back to the circuit breaker.

For example, each circuit breaker controls one area of household lighting. The black white and copper wires leave breaker box in a single romex cable. The romex travels to a junction box in the area where the lights are located. The junction box is usually a switch box or a ceiling box. From the junction box, the romex travels to each other switch, light and receptacle box in the area. So each box has 1 hot and 1 neutral and 1 ground that is connected in a line that leads back to breaker box.

Here's a couple pages that make home wiring easier to understand:
http://waterheatertimer.org/See-inside-main-breaker-box.html
http://waterheatertimer.org/240-v-water-heater-circuit.html
http://waterheatertimer.org/Install-owb.html

The red wire is your chase wire and needs to go all the way to the other switch

one of the white wires has power on it constantly....that wire connects to the black wire of the leviton.......the other white wire which has no power to it is going to whatever needs power so that wire connects to the red wire of the leviton....the green wire connects to the metal box where your mounting the leviton.

I'm not sure if this is going to work in your case, but I'm pretty sure it will...

Green to ground (probably bare)
Black to black
White to the red that's not labeled 3-way
wire nut on the red labeled 3-way

That should fixya!

house has a black and a white line and a ground commper, dimmer has two black and a green
How do I know which blck lead goes to white and which goes to black? One lead is shorter than the other.

one black from the dimmer to black. the other black from the dimmer connected to red. the green connected to the bare wire.

those wires dont go to the down draft. those colors are to hook up the stove. do you have the instalation instructions?