Need help with a simple (I think) Perl script

First of all, I am a rank amateur at Perl. Here is my problem: I have a hundred or more files in a directory on a web server (let's call it 'Library'). Each file is a pdf file and is named 'yyyymmm.pdf' where yyyy is the year (i.e. 2007) and mmm is the first 3 letters of the month (i.e. Jan). So a typical file name looks like '2007Jan.pdf'.