WindyPoint on "A way to see where PHP is rendered?"

I see. It sounds like the PHP server-side script should then have SQL commands in it, to write new data to the database. Right?

I am trying to find out which PHP file gathers the HTML data. In an example I found:

<form method="post" action="claim.php" name="ClaimForm" id="ClaimForm" autocomplete="on">
    <fieldset>
        <legend>Contact Details</legend>
        <div>
            <label for="firstname" accesskey="U">Your First Name</label>
            <input name="firstname" type="text" id="firstname" placeholder="Enter your name" required />
        </div>

etc...

In that first line it mentions the PHP file as claim.php However, the woocommerce plugin is missing that action field:

<form method="post">
    <h3>
        Billing Address
    </h3>
    <p id="billing_country_field" class="form-row form-row-wide address-field update_totals_on_change validate-required"></p>
    <p id="billing_first_name_field" class="form-row form-row-first validate-required">
        <label class="" for="billing_first_name">
            First Name
            <abbr class="required" title="required">
                *
            </abbr>
        </label>
        <input id="billing_first_name" class="input-text" type="text" value="John" placeholder="" name="billing_first_name"></input>
    </p>

etc...

My question then is how to hunt this down. It seems like the environment is working just as you say, but I can not trace it.