How to send mail using php and ajax

<span class="success" style="display:none"> Thank you for your interest. Our team will contact you soon.</span>
<form method="post">
<div class="form apear" style="opacity: 1; transform: matrix(1, 0, 0, 1, 0, 0);">
<input maxlength="15" size="15" class="input-text" id="fname" type="text"name="fname" placeholder="First Name *"onfocus="if(this.value==this.defaultValue)this.value=”;"onblur="if(this.value==”)this.value=this.defaultValue;" >
<input maxlength="15" size="15" class="input-text" type="text" name="" id="lname"placeholder="Last Name *" onfocus="if(this.value==this.defaultValue)this.value=”;"onblur="if(this.value==”)this.value=this.defaultValue;">
<input maxlength="30" size="30" class="input-text" id="company" type="text" name=""placeholder="Company *" onfocus="if(this.value==this.defaultValue)this.value=”;"onblur="if(this.value==”)this.value=this.defaultValue;">
<input class="input-text" id="email" type="text" name="" placeholder="E-mail *"onfocus="if(this.value==this.defaultValue)this.value=”;"onblur="if(this.value==”)this.value=this.defaultValue;">
<input maxlength="15" size="15" class="input-text" id="phone" type="text" name=""placeholder="Contact Number *"onfocus="if(this.value==this.defaultValue)this.value=”;"onblur="if(this.value==”)this.value=this.defaultValue;">
<input class="input-btn" type="submit" value="submit" id="submit">
</div>
</form>

</script>
<script type="text/javascript" >
$(function() {
$("#submit").click(function() {
var fname = $("#fname").val();
var lname = $("#lname").val();
var email = $("#email").val();
var company = $("#company").val();
var phone = $("#phone").val();
var dataString = ‘fname=’+ fname + ‘&lname=’ + lname + ‘&email=’ + email + ‘&company=’ + company + ‘&phone=’ + phone;
if(fname == ”)
{
$( "#fname" ).addClass( "required" );
$(‘.success’).fadeOut(200).hide();
}
else
{
$( "#fname" ).removeClass( "required" );
}

if(lname == ”)
{
$( "#lname" ).addClass( "required" );
$(‘.success’).fadeOut(200).hide();
}
else
{
$( "#lname" ).removeClass( "required" );
}

var email1 = false;
if(email == ”)
{
$("#email").addClass( "required" );
$(‘.success’).fadeOut(200).hide();
}
else
{
var filter = /^[\w\-\.\+]+\@[a-zA-Z0-9\.\-]+\.[a-zA-z0-9]{2,4}$/;
if (filter.test(email)) {
$( "#email" ).removeClass( "required" );
var email1 = true;
} else{
$("#email").addClass( "required" );
$(‘.success’).fadeOut(200).hide();
var email1 = false;
}
/*$( "#email" ).removeClass( "required" );*/
}

if(phone == ”)
{
$( "#phone" ).addClass( "required" );
$(‘.success’).fadeOut(200).hide();
}
else
{
$( "#phone" ).removeClass( "required" );
}
if(company == ”)
{
$( "#company" ).addClass( "required" );
$(‘.success’).fadeOut(200).hide();
}
else
{
$( "#company" ).removeClass( "required" );
}

if(company == ” || fname == ” || lname == ” || email == ” || email1 == false || phone == ” )
{

$(‘.error’).fadeOut(200).show();
}
else
{
$.ajax({
type: "POST",
url: "mail.php",
data: dataString,
success: function(){
$(‘#email’).val("");
$(‘#fname’).val("");
$(‘#lname’).val("");
$(‘#company’).val("");
$(‘#phone’).val("");
$(‘.error’).fadeOut(200).hide();
$(‘.success’).fadeIn(200).show();
}
});
}
return false;
});
});