settings.php

<?php

function mn_settings(){

    get_option('mn_check_sandbox') == 1 ? $sandbox = ' checked="checked"' : $sandbox = '';
            
    if (isset($_POST['mn_submit'])){
        update_option('mn_check_sandbox', $_POST['mn_check_sandbox']);
        update_option('mn_moip_email', $_POST['mn_moip_email']);
        get_option('mn_check_sandbox') == 1 ? $sandbox = ' checked="checked"' : $sandbox = '';
    echo '<div id="message" class="updated fade"><p><b>Options saved!</b></p></div>';
    
    }
    
?>

<div class="wrap">

    <form id="options_form" method="post" action="">
        <h2>MoIP Settings</h2> 
        
        <table style="width: 850px; margin: 20px 0;" id="tblspacer" class="widefat fixed">

    
                <thead>
                    <tr>
                        <th width="200px" scope="col">Edit Settings</th>
                        <th scope="col">&nbsp;</th>
                    </tr>
                </thead>
            
                <tbody>
                <tr>
                    <td class="titledesc" style="padding:12px 7px; vertical-align:top;">
                        <label for="mn_check_sandbox">Enable sandbox?</label>
                    </td>
                    
                    <td class="forminp" style="padding:12px 7px; vertical-align:top;">
                        <input type="checkbox" id="mn_check_sandbox" name="mn_check_sandbox" value="1" <?php echo $sandbox;?> />
                        <br>
                        <small>You must have a <a href="http://desenvolvedor.moip.com.br/sandbox/" target="_new" title="">MoIP Sandbox </a>account setup before using this feature.</small>
                    </td>
                </tr>
                
                <tr>
                    <td class="titledesc" style="padding:12px 7px; vertical-align:top;">
                        Registered MoIP email:
                    </td>
                    
                    <td class="forminp" style="padding:12px 7px; vertical-align:top;">
                        <input type="text" name="mn_moip_email" value="<?=get_option('mn_moip_email');?>" />
                        <br>
                        <small>You must have a <a href="http://www.moip.com.br/" target="_new" title="">MoIP</a> account setup before using this feature.</small>
                    </td>
                    
                </tr>
        </table>

                <div class="submit">
                    <input type="submit" name="mn_submit" id="mn_submit" value="<?php _e('Update Options &raquo;') ?>" />
                </div>

    </form>
    
</div>

<?php } ?>