Hello, stearing the sub takes lots of practice. There are a couple ways to change your heading:
-by ploting a course on the map
-by moving the rudder with the mouse or keyboard
-by clicking on a heading on the compass
-in any pariscope view or from the bridge/deck gun, press the key next to delete (my keyboard is German), and your sub will automatically turn to that heading
-check out this thread (
http://www.subsim.com/radioroom/showthread.php?t=101924) for other ways you can enter commands
-you can't use the arrows to stear the boat. However, there are ways to change the keyboard functions around, but I haven't gotten around to doing that myself yet.
To get the external view locked on your sub, press the key under the 'L' key (sorry). You can also keep pressing it to look at other ships in the area.
I think Bookworm was talking about this thread:
http://www.subsim.com/radioroom/showthread.php?t=96026
It's gives useful tips for newcomers.
Good Luck!