jquery - how to add drop-down field in bootstrap contact form and what changes I need to do in php and contact_me.js? -

here bootsrap code. want add dropdown list i'm not sure how work , changes need in php , content_me.js.

i tried doing changes in php not working.

also, want put add more service button appear when user selects option given drop down. if user clicks add more button button disappears , new dropdown shows up.

<form name="sentmessage" id="contactform" novalidate>  	<div class="row">  		<div class="col-md-6">  			<div class="form-group">  				<input type="text" class="form-control" placeholder="your name *" id="name" required data-validation-required-message="please enter name.">  				<p class="help-block text-danger"></p>  			</div>  			<div class="form-group">  				<input type="email" class="form-control" placeholder="your email *" id="email" required data-validation-required-message="please enter email address.">  				<p class="help-block text-danger"></p>  			</div>  			<div class="form-group">  				<input type="tel" class="form-control" placeholder="your phone *" id="phone" required data-validation-required-message="please enter phone number.">  				<p class="help-block text-danger"></p>  			</div>  			<div class="form-group">  				<select class="form-control" name="service" id="service">  					<option>--select service--</option>  					<option value="1">option 1</option>  					<option value="2">option 2</option>  					<option value="3">option 3</option>  					<option value="4">option 4</option>  				</select>  				<p class="help-block text-danger"></p>  			</div>  		</div>  		<div class="col-md-6">  			<div class="form-group">  				<textarea class="form-control" placeholder="your message *" id="message" required data-validation-required-message="please enter message."></textarea>  				<p class="help-block text-danger"></p>  			</div>  		</div>  		<div class="clearfix"></div>  		<div class="col-lg-12 text-center">  			<div id="success"></div>  			<button type="submit" class="btn btn-xl">send message</button>  		</div>  	</div>  </form>        <?php ob_start();      // check empty fields  if(empty($_post['name'])      ||  	empty($_post['email'])     ||  	empty($_post['phone'])     ||  	empty($_post['message'])   ||  	empty($_post['service'])   ||  	!filter_var($_post['email'],filter_validate_email))  {  	echo "no arguments provided!";  	return false;  }    $name = $_post['name'];  $email_address = $_post['email'];  $phone = $_post['phone'];  $message = $_post['message'];  $service = $_post['service'];        // create email , send message  $to = 'yourname@yourdomain.com'; // add email address inbetween '' replacing yourname@yourdomain.com - form send message to.  $email_subject = "website contact form:  $name";  $email_body = "you have received new message website contact form.\n\n"."here details:\n\nname: $name\n\nemail: $email_address\n\nphone: $phone\n\nmessage:\n$message\n\nservice:\n$service";  $headers = "from: noreply@yourdomain.com\n"; // email address generated message from. recommend using noreply@yourdomain.com.  $headers .= "reply-to: $email_address";     mail($to,$email_subject,$email_body,$headers);  return true;           ob_flush();?>