how to save a field created by using hooks in database
first create submit button

$form['submit_button'] = array(
                '#type' =&gt; 'submit',
                '#value' =&gt; t('Click Here!'),
                );


when you create submit it calls this function and feilds submitted or updated to your database

function form_try_form_submit($form, &amp;$form_state) 
            {
                echo '&lt;pre&gt;';
                var_dump($form_state['values']);
                echo '&lt;/pre&gt;';
                $insert=db_insert('DB')
                -&gt;fields
                (
                    array
                    (
                        'phone' =&gt; $form_state['values']['phone']
                                 ) 
                 )
            }