There are two ways you can change file permissions.

Use a chmod.php file

To change the read or write permissions of a file, you can use the PHP function chmod(). To make a file readable and writable for the owner, and readable for everybody else, for example, you might create code like this:

Please note that you will not be able to change the file permissions of any of your files to make them executable. You can run your PHP scripts, which are indicated by the .php file extension, without making them executable.

Use an FTP client

You can connect to your account using an FTP client, then right-click the file or folder name which you want to change. You should find a Properties, Info, or Permissions choice on the menu that appears. Check the help pages for your FTP client for details.