<link href="//maxcdn.bootstrapcdn.com/bootstrap/4.1.1/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css">
<script src="//maxcdn.bootstrapcdn.com/bootstrap/4.1.1/js/bootstrap.min.js"></script>
<script src="//code.jquery.com/jquery-1.11.1.min.js"></script>
<form class="form-horizontal">
<fieldset>
<legend>Form Name</legend>
<br>
<div class="form-group">
<label class="col-md-4 control-label" for="First Name">First Name:</label>
<div class="col-md-4">
<input id="First Name" name="First Name" type="text" placeholder="" class="form-control input-md" required="">
</div>
</div>
<div class="form-group">
<label class="col-md-4 control-label" for="Last Name">Last Name:</label>
<div class="col-md-4">
<input id="Last Name" name="Last Name" type="text" placeholder="" class="form-control input-md" required="">
</div>
</div>
<div class="form-group">
<label class="col-md-4 control-label" for="Contact">Contact:</label>
<div class="col-md-4">
<div class="input-group">
<span class="input-group-addon">+91</span>
<input id="Contact" name="Contact" class="form-control" placeholder="0000000000" type="text" required="">