Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request. Please contact the server administrator, support@supportwebsite.com and inform them of the time the error occurred, and anything you might have done that may have caused the error.
More information about this error may be available in the server error log.
Basically, the easiest way is to log into your FTP client (I prefer FileZilla) and an the directories you want to CHMOD, right click and select properties or permissions, whatever it comes up as and change to 0777 or 0755