and find this code and where i added TRY TO ADD YOU RHTML HERE, you can add your html there to add new labels.
$content = '<div class="invoice-box">
<table cellpadding="0" cellspacing="0">
<tr class="top">
<td colspan="2">
<table>
<tr>
<td class="title">';
if(!has_custom_logo()) {
$content .= '<h1 class="site-title">'.get_bloginfo( 'name' ).'</h1>';
} else {
$computer_repair_logo = get_option("computer_repair_logo");
$content .= '<img src="'.esc_url($computer_repair_logo).'" style="width:auto; max-width:100%;height:60px;" />';
}
$content .= 'TRY TO ADD YOUR HTML HERE TO APPEAR BELOW LOGO</td>