You must create full packages for error pages.
Here's the list of error pages you must create :
400 Bad Request - HTTP_BAD_REQUEST
401 Authorization Required - HTTP_UNAUTHORIZED
402 Payment Required - HTTP_PAYMENT_REQUIRED
403 Forbidden - HTTP_FORBIDDEN
404 Not Found - HTTP_NOT_FOUND
407 Proxy Authentication Required - HTTP_PROXY_AUTHENTICATION_REQUIRED
408 Request Time-out - HTTP_REQUEST_TIME_OUT
500 Internal Server Error - HTTP_INTERNAL_SERVER_ERROR
502 Bad Gateway - HTTP_BAD_GATEWAY
503 Service Temporarily Unavailable - HTTP_SERVICE_UNAVAILABLE
504 Gateway Time-out - HTTP_GATEWAY_TIME_OUT
505 HTTP Version Not Supported - HTTP_VERSION_NOT_SUPPORTED
So you only create 12 pages and '.htaccess' file. Each pages must be stored on separate folder.
If you have any skill to do it, just bid it. Don't ever bid if you don't understand.
Project must be completed on 2-3 days. Payment will be issued after the project is finished.
If you need more detail about this project, or any question, just PM it to me.