The main simulation scripts are in the scripts_a2c, scripts_ddpg, scripts_dql folders. The most recent scripts should run with no problem. The older ones are probably broken.
In order to make your own scripts, just create another scripts_ folder, or place your script file into one of the existing ones. It is recomended to look at the already existing scripts for examples and guidelines.
The simulator core functions are placed into the sys_simulator directory.