cpanel is normally a feature provided by your web hosting service. If you need help with it you should contact them and ask. Normally there will be instructions provided with cpanel so you might try looking thru them to see how to deal with uploading content to the site.
I cannot speak for what you might have, but in my case, if you are able to log in to your cpanel, look in the Files section for the File Manager and access that. If you poke around within that you should find the option to upload files.
How do I publish my Flash Slideshow and extract html code? I appreciate your help.