Here is a series of videos that Michael Walker have done for setup and timing of a race.
DTRIS 2.1.9 Part 1 – Choose Race from Michael Walker on Vimeo.
DTRIS 2.19 Part 2 – Timers and Displays from Michael Walker on Vimeo.
DTRIS 2.1.9 Part 3 – Timing a race from Michael Walker on Vimeo.