I have never seen a elite 4, the elite-5 has a memory card slot where you can install a navionics or lakemaster chip that will give you a depth chart. They are not uploadable into the memory of the unit like a HDS series. So the card has to be install so the unit can read the card and display the info.
Also you might want to set your heading to "course or track up" as they typically come in "north up". With course up, you/arrow are always headed up the screen so what ever is on your left is on your left/right is on your right. You can also set your "overlay options" on both your gps and depth screens. This allows you to see your depth while looking at the gps screen/your speed while viewing your fishfinder screen. Also set it up for your split screen. Along with time, temp etc. The elite should already be set to mark/show your trail as you go you have to manually delete the trail at the end of the day unless you want to save it. It only takes a couple seconds "delete trail".