C-Shell

Hi All,
I need a script for the C-shell.
It is used as follows:
The script is run on the command line and three command line
arguments are specified: a filename and two letters.
The script reads the file and analyzes it: For each letter from the
first to the second it determines how ofter the letter occurs in
the file and prints this. Example: The user types?? scr poem b h
The script analyzes the file poem for the letters from b to h
and prints the result in the form shown below:
?b?? c?? d?? e?? f?? g?? h

23? 12? 55? 17? 16?? 8?? 5
The letters have a distance of 3 spaces from each other, the
line stretches from the first to the last letter, the numbers
are exactly under the letters.

Programming hints:
1) Put the file contents in a local shell variable
2) Remove all spaces (tr command)
3) Make all letters lower case (tr command)
4) Remove all characters that are not letters from a to z.
5) For each letter in the specified range find their frequencies.
6) Print the letters in the range
7) Print a line of '=' of the exact length
8) Print the numbers under the letters

Thanks in advance.

please don't post homework questions. thread closed!