Checking valid shirt ID by _GET and if
Or like this valid shirt redirect!

If else by $product varible.
Redirecting Invalid Shirt IDs

if (!isset($product)
header("Location: _location_ ");
http://www.faqs.org/rfcs/rfc2616.html
Adding Available Sizes

foreach array in array
Creating the Shirt Display Function

Display Function with custom function
Displaying Only Four Shirts

Home page prevew.
You must specify a value.

You must specify a value for name, email address,  and message.
In the form.
Email Header Injection Exploit

http://nyphp.org/phundamentals/8_Preventing-Email-Header-Injection
Using A Third-Party Library

https://github.com/PHPMailer/PHPMailer
Sending The Contact Form Email
Test
Test1
Ovo je proba koding editora
End  of Tutorial
The End