ksh - An agenda in Korn Shell: New / Edit / Delete / View appointment -

As stated in the headline, I have to write a simple script which should do some general agenda. The script should use the crontab.

Create a list of appointments

I have no clue how to do this, Can you help me with some hints?

Edit: To be more specific on my question

Issue 1: How can I edit a crontab thorugh ksh? How do I insert a new line? Can you link to some document or code about this? Here is some code that adds a script that runs at 7:30 in your cronch:

/ P>

  typeset CURRENT_CRONTAB = $ (crontab -l) # The current crontab has a variable print "$ {CURRENT_CRONTAB} 30 07 * * * / home / tomd / my_script.ksh" | Crontab -  

yours,
Tom