There are several ways you can do this.
GMAX is one way of making scenery
FSSC is another
XML is another way but some what complicated.
And there are others out there if you look through the posts in this section you will see what i mean.
Some of these can be hard to master it depends on how much you understand about computers and the different langauges they use.
If you have little or no knowledge of computers you might find these programs rather difficult but not impossable 8)

Have a look here...

Gmax: http://www.discreet.com/products/gmax/

FSSC: http://www.fssc.avsim.net/

EOD:  http://www.echos.ch/eod/

Regards,
Stratobat