Filezilla is a file transfer programme which is more commonly referred to as FTP. It is an open source programme which is free and above all is extremely easy to use and install.
The best way to find it is simply to Google Filezilla and you will arrive at a download page. Just one word of warning at this point, make doubly sure that you spell filezilla correctly. There are some dodgy websites that have been set up with similar spelt domain names to catch the unwary, if you are not careful...