Hi Jenny Zhu,
Welcome to the forum!
After installing VC and runing a job, the log of this job is saved in a global log file in the log folder in the application directory.
You can also request the job log in VC by selecting the job and request the log using the context menu.
In the flow tab of the job/task you can also tell it write its output to a phisical file.
Regards
Erik
Uses Visualcron since 2006.