Date and time by PHP

i am new in php but i have created the below code on my webpage to show the date, but its not working.
i want to see a simple format of date and time.want to know why?

    echo date("l");
    echo date('l jS \of F Y h:i:s A');
    echo "July *, 2000 is on a " . date("l", mktime(0, 0, 0, 7, *, 2000));
    echo date("DATE");
    echo date(DATE_ATOM, mktime(0, 0, 0, 7, *, 2000));