ActionScript 2.0 :: Classes Talking To Each Other

Now I am trying to another very simple thing.

In my main time line I have:
var _side = new Side();
var _main = new Main();

I have Main.as and Side.as saved in the same folder as Main.fla.

Here is Main.as

ActionScript Code:
class Main {
public function Main(){

[Code]....

Now the Main.as knows nothing of the variables speed and velocity. Is there a way to reference back and forth? Say for instance I have a dog class that drinks water from the water class.

If it rains then the water class changes var Water from 4 to 8; When the dog drink the water he can drink until the water is gone, but how the water variable was changed in the water class not the dog class.