Jim,
Do you want the trains to start and stop with block signals automatically? If so Barrys book will not help you.
Although DCS cannot modify engine behavior based on external devices, such as block signals, one can simulate that using the DCS Record/Playback function.
The DCS O Gauge Companion describes the Record/Playback function in quite a bit of detail.
Regardless, ROZY stated that he is "... trying to run 2 trains at the same time on continuos track, how can I get 1 train to stop & let the other one go by ?"
As was pointed out above, this is easily done just by using the DCS Remote normally. My point in suggesting that the book would help, is based on these types of questions, which lead me to believe that he really doesn't quite have a handle on command control or the kinds of things of which DCS is capable.
All "pride of authorship" and "false modesty"aside, the book is exactly what he needs.