No matter what version of ILlustrator, I prefer using layers. If you open the Layers paletter and make a new layer. Drag it to the bottom of the layers palette. Select the layer and draw a rectangle filled with color on that layer. You can then lock the layer and draw on the other layers without touching the background.
Conversely, you can lock the other layers and unlock the background and change the background color to whatever you choose. Experiment.
The HELP file will tell you more about layers.