x-plane

I have just bought x-plane and am having problems with it. I am a
retired pilot so am at home with aviation terms but find parts of the
application itself difficult to follow.

Firstly, none of the civil aircraft seem to have any DME indications
The C-119 Boxcar, a favourite of mine, has an OBI but no 'to/from'
indicator
The FMS is obviously very complicated but I can't find a guide to its
use.
Building the 777 as suggested in the manual is beyond me at present.
For example, I select the DME gauge to drag it to the panel but cannot
make it active.
On the World Atlas, it says 'zap' the screen to prevent positionng the
aircraft. How do I zap something?

Be much obliged for any advice

David Carpenter