I just installed an A/C unit to my furnace. I want to confirm where the relay wires go as well as the other thermostat wires.

Furnace has C W R G Y terminals.

Thermostat has W R G Y terminals.

There are four wires running between them, and two are hooked up. They are White - from W to W
And Red - from R to R

The other two wires are not attached to the furnace but I assume go:
Blue - Y to Y
And Green - G to G

By reading past threads I believe the Y is for cooling and G is for fan control?

Where do I tie the two wires from the A/C relay?

Most thermostat cables have a yellow wire connecting the Y at the thermostat to the y at the furnace. If a blue wire is all you have, use it, electricity is color blind. The 2 wires from the relay coil go to the furnace Y and C. Again color is only to help you tell which wire is which. It is floating AC so which is which makes no difference.