Processing kinds with php to wordpress database

I am merely making an attempt to course of information from an html type into my wordpress database by means of php. I’ve tried a number of instances to get the information inserted however have had no luck.

The setup is as follows:
Database identify: seanmcve_AssociationNation
Desk: affiliation
The row I need information entered in: association_first_name

I’ve setup a web page template referred to as form_processing_template.php.

<?php
/*
Template Identify: type processing template
*/
?>

<type motion="" methodology="submit">

<h4><sturdy>What's the authorized identify of your affiliation?</sturdy></h4>
<enter identify="legalName" sort="textual content" placeholder="Affiliation Identify" />
<enter sort="submit" identify="submit" worth="Submit" />
</type>

<?php
If($_POST['submit']) {
// run validation when you're not doing it in js

$legalname=$_POST['legalName'];
echo $legalname;
$wpdb->insert('affiliation',
        array(
                'association_first_name' => '$legalname'

            ),
            array(
             '$s',
             )
);

}
?>

<?php x_get_view( x_get_stack(), 'wp', 'web page' ); ?>

I am echoing the variable simply to verify it is appropriate and dealing (which is working) I have been referencing the wpdb class reference web page and nonetheless have had no luck. Can anybody level me in the suitable course?