Go here:
http://x10hosting.com/panel.php
Log in using your forum user name and password.
There will be a link on the page after you log in to CPanel
Log in using your CPanel name and password (your CPanel name is on the page with the link)
Find the "File Manager" tool in CPanel
Upload your files to the public_html folder.
Any file you upload to public_html will be viewable on your site. In example:
public_html/file.hml will look like mysite.com/file.html