I have file problems that do not open when I upload them

Hi I'm having problems uploading files
I have some problems I can not change the PHP versions and I have some files do not TFT for example
http://3px.pw/compatibility.php

3px.pw website is not working for me.   

You can now view the active site please help me

Internal Server Error

The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator at aypp2015@gmail.com to inform them of the time this error occurred, and the actions you performed just before this error.

More information about this error may be available in the server error log.

as the error messages says you need to check error_log file and then see what to do next.
http://wiki.centos-webpanel.com/service-log-paths

Mostly this issue is related with incorrect file owner permissions on the files you uploaded so you can use Fix account permissions option in CWP under user accounts.