READING INPUT FROM A FORM
That's your new best friend (unless you use the GET method).
Let's assume that somebody has entered some text into a form you created on your initial HTML page, and that you named the 2 text fields "name" and "email".
The PHP page that is defined in the action of the form can print this info with this code:
echo "Hello $_POST[name]
echo "Your address is $_POST[email]";