Try a surfaced attack to start with. This way you can click on the watch officer and he will give you range. Its difficult to learn all aspects at once. After you learn about AOB and plotting the targets track you can then go on to estimating range using the stadimeter later. I did up a tutorial concerning parallel manual attacks not that long ago. The screens may look different as it was done in a modded game. But otherwise the steps are identical. Check out this thread:
http://www.subsim.com/radioroom/show...eting+tutorial
I should have pointed out where to click to get range updates. After you click the icon for the Watch Officer, seven white icons appear above him to the left. The 2nd one from the right will give you the range to nearest target.