Click on the topology tool - the one in the upper right corner.
Get the height of your ground.
Click on water and set the height to be something higher than your ground.
Adjust the size of the brush.
Paint in the water.
There is no way to fill the grid with water.
If you've already painted water and it doesn't show, it means you have buried it under the ground.
Click on the area where the water should be.
click on the water with the + + on it and raise the mouse up. This will raise your water up to where you want it.
Hope this helps.
