Problem with uploading stylesheets

Hi Not sure if anyone can help, but I'm trying to upload my simple website via cPanel and I have problems... Inside my computer, the pages of my site all show up in nice fonts with the right coloured backgrounds, exactly as I want them. When I upload these exact files (which have a Chrome logo) they appear as simple html on the Internet. As part of my attempt to investigate this, I downloaded a 'Simple Style' template onto my computer. When I opened it, that too was just showing up in html. Any ideas what I'm doing wrong?