where do you get HTML code to make a "Log-in" box on your website?

Answer 1

Use a form from Coldfusion..

Click on " 6. Rich Forms "

http://www.adobe.com/products/coldfusion/productinfo/features/whatsnew/

Answer 2

Well creating a form is easy, making it worth something is a different issue. What exactly is the user "Logging Into" the form needs to direct them to something. Generally this means you have a database sytem to record the login and then have the login take the user to "protected pages" or new content that is not otherwise available.
Just to create a login makes no sense to me.
If you want a dynamic site with a real login why not use one of the content management systems (like phpNuke or phpwebsite, or etc etc) they already have a login box which does something.

Now if all you want is to force someone to login to view your site use .htaccess file and require login. (or simple php code in the top of your page for login)