As long as where you put the files are accessible by http requests it will work. I'm not sure how your website is set up, in many cases the default for websites are /www/htdocs (linux servers that is). Everything under /htdocs is readable by an http request. So, ftp your file to /www/htdocs/ringtones and it should be able to be gotten to by http://yoursite.com/ringtones/nameoftone.mid
A simplified explanation here, but it should get you on the right track.