Go to the schemtic editor and name your ground wire as "GND" or something like that by pressing F9 on the wire.
Now go to the Layout editor select the polygon tool then select "filled polygon" in the top left corner, select polygon net as "GND" and then draw your polygon. This new polygon will act like you ground.
You can have as many of these copper pours as you want. Take a look at the attachment where T+, T- and the Start button grounds are connected with a polygon.
- pour.gif (13.42 KiB) Viewed 2494 times