Hi.
What do pro trail builders use ? Is there some sort of software ?
As suggested, try and use the existing terrain and see if it suggests turns at certain sport and needs berms, etc. Id guess a problem with runs that arnt real steep/high is that all the speed can be sapped up.
Ive not build jumps myself but they arnt too hard I would of thought, getting berms in is gonna be harder/involve more digging.
http://www.wikihow.com/Make-a-Mountain-Bike-CourseTheyve built lots of new trails near me on (and outside) the Olympic XC track area, perhaps take a visit to get some ideas (although clearly they have spent a lot of time and money, completely laying down new surfaces, etc)
Heres a vid clip i did >