Thanks for the help.
I have work on the code as per your suggestion, however the time i run the code and click on login to display siginin div, it doesn't display signin div so i change it to $("#signin").show();, even though it doesn't display the signin div
also when i click on login button it does'nt validate through login.php infact it does nothing.
In following code
$username = mysql_real_escape_string($_POST["name"]);
$password = mysql_real_escape_string(md5($_POST["pass"]));
I have change name to username, and pass to password
because my textfield value is username and password
please give me some suggestion