[TECK]

That's fine, you will use only one site, I'm pretty sure.
Now test to see if it works.

Go to C:\inetpub\wwwroot folder and delete all files/folders in there.
Create a new file called index.php, with the content:

</php

phpinfo();

?>

Now, into your browser, open this link:
http://localhost/

You should see the default PHP configuration file with all options enabled.
First look at this option:
Configuration File (php.ini) Path: C:\inetpub\php\php.ini
If it shows this, scroll down and let me know if you see there a section called mysqli.
(search for it with a CTRL + F, faster)

If you do, PHP is installed properly.
We can proceed with MySQL install... almost done.