function CheckLogin() {

    if (document.getElementById('txtUserName').value == '') {
        alert('Please enter User Name');
        document.getElementById('txtUserName').focus();
        return false;
    }

    if (document.getElementById('txtPassword').value == '') {
        alert('Please enter Password');
        document.getElementById('txtPassword').focus();
        return false;
    }

    var pass = document.getElementById('txtPassword').value;
    if (pass.length < 6) {
        alert('Password must be 6 characters long.');
        document.getElementById('txtPassword').focus();
        return false;
    }
}