Creating commands in C-shell

Hey guys, I'm writing a C-shell command and I want to give the user options when running the command for example I'm trying to make a command that compresses all of the files in a directory with a user defined extension (.txt .pdf etc...) that's over a specific size and using either a default program to compress the file.

This is what I have so far

#!/bin/csh

if ($2 == "") then
#Check if the second argument is empty
   echo "This shell script compress files with a specific extension"
   echo -n "Call syntax: minimize [-s size] [-p prog] <directory> "
   echo "<ext_list>"
   echo -n "Where what is between [and] is optional whereas what is between "
   echo "<and> is not."
   echo "Example: minimize -s 10000 -p gzip ./ ps pdf"
   echo -n "All files in the current directory over 10000 bytes with the "
   echo "extension ps or pdf will be compressed using gzip"
   exit
endif

if (-d $1) then
#Check if the frist argument is a directoy
    echo "This is a directory"
    echo "files will be compressed"
        foreach file (`$1`)
#Look at each file in the user specified directory
                if ($file =~ *.$2) then
#Compress all files in the specified directory that match the extensions in the second argument specified by the user
                compress $file
                echo $file "has been compressed"
                endif
        end
else
    echo $1 "is not an acceptable directory"
    exit
endif

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I just fundamentally don't understand how to set up options, any advice?

god that looks like shit, so that's C-shell uh? nice to meet it now die shitty language, you do not deserve the C in the name