Redirection???

[apol]

1.User fill in and submit sign_in_form.php

2. sign_in_check.php check if submited form is valid (userName & passwd)

    if (form is valid)
          redirect user to the index.php page
    else
          echo 'not valid inputs...';


How can i do the redirection?

thanks

[vbnullchar]

Header("Location: Index.php");