Your problem is relatively simple - it boils down to three things: (1) how to make a directory with a given name, (2) how to do something for every value in a given list of values, and (3) how to generate the range of string values 'a' to 'z'.

The first part is quite easy to do. There's a Perl built-in function called mkdir.

The second part uses a Perl structural building block for looping, or "iteration". It looks like this:

    foreach ( values )
    {
        do something
    }

This raises a question: How does the code inside the code block (which is delimited by the curly braces) know which value in the list is the right one for the current iteration? Well, by default, the foreach construct sets the special variable $_ to each value in the list, in turn. So do something merely needs to access the $_ variable to get the current value.

The third part is somewhat more magical, but fortunately the syntax is quite simple. Using the so-called "range operator" — which is simply written as two dots (..) — between a start an and end value, perl automatically generates the entire list of all the values in between them.

Now, putting it all together:

    for ( 'a' .. 'z' )
    {
        mkdir $_;
    }
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If you throw this in a text file and run perl on it (e.g. perl mkdir_a2z.pl), it will do what you want. However, there are lots of things you could do to make it "better", such as adding the ability to accept arguments (perhaps to specify the start and/or end directory name), error checking/handling, and reporting. If you need this to be run in a CGI script, that adds a whole 'nother layer of complexity as well.