Usually for a ground plane, you'd draw a polygon, right click on it and Name it Gnd. Then Ratsnest to fill it in and complete the Gnd connections.
I draw them (top & bottom layer) just outside of the dimension lines so you can rip them up & see traces better. You can see the blue & red dotted lines here.
The Unrouted lines are pads that will connect to the ground plane when Ratsnest is clicked.
