If you have any questions, be sure to write me off-list, and I'll see if I can help! If you want, I can come up with some more exercises for you for the computer.
I have a nice Mk.III myself. Interesting thing is it is the early version where the lid flips back towards you- the same as the one shown in the Air Navigation manual from the RAF. Mine is nicely AM marked Canadian made by the "Stanley Manufacturing Compny Ltd. Toronto Canada". I was surprised to discover that the "proper" name for the device is the "Dalton Dead Reckoning Computer Model G", as the original E6B which I have mentioned, (and which Chris offered the directions for), was designed by a US Navy aviator named Dalton, his original device being called the "Dalton Dead Reckoning Computer". I had not realized it, but apparently the Mk.III and E6B are not just very similar, but the same item! I realized this when reading through the web page I gave you the link for in my first posting. It is very clearly marked on the face of the base- Does yours have this marking as well?
On the back, below the AM and crown, mine is marked "SEC.REF. No. 106B/51" then "DEM No."AIR 1124" and "SERIAL No. XY16886"
Do you have the pad of navigational observations on yours? It should be secured to the inside of the lid. The top line is for wind information: first entry is altitude, then speed, then direction. The next 3 lines are for course information: waypoint to waypoint, then IAS, the true course(track) the course you are actually following, ground speed, distance between points and time you actually hit them.(Times are usually given in "Zulu" or GMT, Greenwich Mean Time, and in 24 hour rather than local and 12 hour times)