I'm trying to learn how to set up a cron jobs or scripts that automates some stuff for me. Does anyone know of a good site for learning more about how to create your own cron jobs and scripts? I've been googling quite a bit, but can only find ultra-specific howtos, like rsync stuff.

Cron job 1:
Video files converting:
1) Monitor /folder1 for videofiles
2) Using ffmpeg or mencoder to convert the files to stereo audio and 480p
3) Move the converted files to /folder2

Cron job 2:
Delete non-mp3 files
1) Monitor /folder3 for non-mp3 files
2) Delete them

1) Let user select working folder
2) Let user write what should be removed from filename of all files within folder