Whatever your license status (demo, S1 or S2), you cannot create custom maps or tracks (or cars for that matter).
In the AutoX area, assuming you have the appropriate license rights, you can place objects (lines, tyres, cones, barriers, etc) to layout a track shape (in the form of a 'corridor' that you follow) on the tarmac (and certain sections of grass). You can also place objects on the normal LFS tracks.
The best that can be done for 'custom' tracks are using the open configurations of the existing LFS tracks. For instance on Kyoto, instead of just having KY1, KY2 and KY3, in the open configurations the barriers between certain parts (routes) of the track have been removed, and you can place barriers to force drivers to take a different route.
The LFS community has now given some of these routes their own standard track configuration abbreviations, such as K21, K31, K32, etc. See
HERE for more info.
