help urgently for a code

Don't forget the QuartusII feature, when editing a VHDL file, you can do the menu pick edit -> insert template. If you plop down a whole design example, you can use that as a syntax framework. Or, if you are familiar with emacs as a text editor, it will keep you on the right track as well. After that, it's just "work"

have a read in wikipedia - there should be enough there to help you out