Go to System → Settings → System
Because every system is setup differently, phpinfo() is commonly used to check configuration settings and for available predefined variables on a given system.
Outputs a large amount of information about the current state of PHP. This includes information about PHP compilation options and extensions, the PHP version, server information and environment (if compiled as a module), the PHP environment, OS version information, paths, master and local values of configuration options, HTTP headers, and the PHP License.
For example, you may need to update your php memory_limit to prevent certain scripts from running out of memory. In order to change these values, you must first be able to see what they are.
To find the specific php value, search the page for what you're looking for. In this case, we used our browser's search feature ( Ctrl+F ) and searched for memory_limit. The first value you see is what is set for the current directory (local value), and the setting value is the master value. The local value is the actual setting and is the important value, because the local values will override the master value.
If you see blank page this mean your hosting provider do not allow you to see php.info
Please note that your phpinfo has many php settings that you don't want to broadcast to the world.