I'm not entirely sure what part you need help with. Could you post the code that you have (working or not) and be a little more specific?

If you're starting from scratch, the following may help:

• the angle bracket operator to read from STDIN (see I/O operators in perlop)
• @ARGV - the array that holds parameters from the command line (see perlvar)
• Getopt::Long or Getopt::Std - for more powerful handling of command line arguments
• uc - to uppercase an expression
• ucfirst - to uppercase the first letter of an expression
• m// - for pattern matching (see perlop, and note the i modifier to match case-insensitively)
• s/// - for pattern matching and replacing in a string(see perlop)
• if...else blocks - to add conditionals to your program (see perlsyn)

That should get you started. Good luck.

Update: Added s///