Simple questions –> Custom Plugin integration

I have created a vary simple form that needs to write to the database.

2 Things i need to do
1. When the submit button is clicked write to the db
2. Add a link in the admin menu, either in the dashboard or otherwise so the form can be easily accessed.

here is my code so far

<?php 

/*
 Template Name: connect
 */

if (isset( $_POST["flag"]))
{
global $wpdb;
$id = $_POST["a"];
$id2 = $_POST["b"];

$query = "insert into wp_custom (id, id) values(".$id1.",".$id2.")";
echo $query;
$wpdb->query( $query );
}else{
//inside the function list_id is the form. the action for the form is to post to itself
list_id();

}
?>

If someone could help i would really appreciate it
Ilan