Originally Posted by WeirdHomer

First of all, the file is in ZIP format so it is designed for Windows servers, make sure you are not on a linux server.
Secondly, you say you have shared hosting. Putty is a SSH/TELNET client and most hosts don't allows ssh or telnet access on a shared server so i think you might need to contact your host for it.
Third your public_html directory should be there when you ftp to your hosting space, if you don't see it, try going up one dir (click the two dots "..").

Hope this helps.