Uploading to a www. extension

Sorry I may have the wording wrong, but i'm not a tech... is it possible to upload to a www site? Let me explain, I have a new client who's site is hosted by www.ils.net and I called and asked for the FTP information because I'm doing this woman's rebuild. They gave me...

www.ils.net
clientuser
clientpass

I put that into Smart FTP and am getting an error saying that it's an invalid site. I tried ftp.ils.net and am getting the same error so I called ILS again and he said that is infact correct and that I need to upload to www.ils.net using the clients username and password.

hmmmm.....

This isnt' the first site i've built, but this is the first time i've tried to upload to a www site (does this make sence?)

Does SmartFTP support such uploads, or is there a setting someplace I need to check in order to upload? I'm at a loss.

Thanks for your help.