Integrate javascript into html page

I have a simple html file with an internal javascript. The purpose of the javascript is to evaluate an entered number og output a sentence depending on which kind of vanity phone number it is. The html and the javascript is already working. I want the script separated into an external javascript file. This is a very simple task if you know javascript - max. 0,5 hour. I want the external javascript file integrated into another html website - this one: [login to view URL] The template can be downloaded here: [login to view URL] T his html page design already have an input field and a calculate button in the layout. The task is to make the javascript work with the existing input field and click button. And to make the result show up below the input field in the same font and size as the text just above the input field. Look at the enclosed screen dump Furthermore I want the contact form working so it can send emails to me.