[HELP]I was asked to do this script, but I really have no clue.. help me pls

Exercise to create a shell script which interactively (by asking user for values) creates a csv file containing the data (e.g. lastname, firstname, age).

• The file path is provided by command line parameter
• several kinds of problems should be handled (clear error message, options to proceed):
  
  
  
  • directory is not existing: ask if it should be created or script should terminate
  • file name empty - put in interactively or terminate
  • file already exists - overwrtite or terminate
  
  
• if the file path is already existing, the user is asked if the file should replaced or the script should terminate.
• The first line contains the column names, e.g. 'Last Name;First Name;Age'
• The script is able to gather an arbitrary number of person data records.
• End is indicated by a '#' as input for the first field (e.g. lastname)
• CSV file is a list of person records, one per line. the fields are separated.by ';' e.g.: Müller;Heinz;23