Windows Control panel Documentation (SolidCP/WebsitePanel)
You can find documentation for WebsitePanel (Also applies to SolidCP) from:
User guide: http://www.websitepanel.net/documentation/users-guide/
Reseller guide: http://www.websitepanel.net/documentation/resellers-guide/
Linux Control panel Documentation (Cpanel / WHM)
For users new to cPanel, please visit the quick start documentation: http://www.cpanel.net/docs/cpanel-qs/
Full documentation can be found at http://www.cpanel.net/docs/cpanel/
For Resellers, please visit http://www.cpanel.net/docs/whm/ to view the documentation for Web Host Manager (WHM).