Why my PHP script is not running in website

I am C++ develoer and new with web. I bought web space and DNS, when I try to upload HTML changes they are getting reflected on my website, but when I right any PHP script and upload file no changes are getting updated. I am using FileZilla for FTP. Do I need to follow some directory strucutre?

Solution

If the server has PHP support than you should be able to place .php files anywhere you can place .html files and it will parse them.

Make sure you have PHP support on your server
Make sure that the files are placed where you place your normal html files
Make sure that the files have an extention that your server is setup to use (default is .php)
Make sure the PHP inside the files is contained in <?php and ?>