$.ajax({
    type: "POST",
    url: "SendEmail.aspx/SendMyEmail",
    data: '{EmailFromAddress: "mike", EmailFromName: "mike", EmailSubject: "email subject here", EmailBody: "email body here"}',
    contentType: "application/json; charset=utf-8",
    dataType: "json",
    success: OnSuccess,
    failure: function (response) {
        alert(response.d);
    }
});