Hi,
Try the following script in login Page-
<script>
$(document).ready(function() {
$(document.loginForm.loginName).focus(function() {$(document.loginForm.loginName).after("<span>Enter Email Id</span>")});
$(document.loginForm.password).focus(function() {$(document.loginForm.password).after("<span>Enter Password</span>")});
$(document.loginForm.loginName).focus();
});
</script>