script1.js

$(document).ready(function(){
    $("#btn").click(function(){
      var username = $("#username").val();
	  var password = $("#password").val();
	  $.ajax({
		  type: 'POST',
		  url: 'alma.php',
		  data: {username:username, password:password},
		  success: function(data){
			  $('#feed_back').html(data);
		  }
	  })
    });

});