In the Creation toolbar, click once on River/Ocean.

The first thing we' ll need to do is ‘assign' the riverbanks, by using the Channel Definition Property Page.

Select River_0 in the Scene Tree.

In the Properties Tree, click on Select Shores.

Click on Left Shore, and then select SkeletonLine_Riverbank_Left.

Click on Right Shore and select SkeletonLine_Riverbank_Right.

We should also be able to see the Flow arrows, indicating the direction in which our river will be flowing.

If the river is flowing upward, or in the positive Y direction, click on the Reverse Flow button in the River's Channel Definition Property Page.

NOTE: If you get an error message about Mesh Steps, don't worry. Just select Settings in the Properties Tree and change the Mesh Step parameter from the default of 15 to 0.5. You'll notice the Vertices Number value rise or fall in accord with the settings; at a Mesh Step setting of 15 the Vertices Number will probably be zero.

Select River and then select Height Above Surface (Properties Tree). Keep in mind that the river should be no higher than the Skeleton Lines defining its banks (otherwise it would be flooding!).

Set the Height Above Surface value to be a little lower than that of the left and right riverbank Skeleton Lines.