Freeze menu and link to anchors

Hello,

I am trying to create a website which has a single long page with different sections(not different pages). For example "product, applications, workflow, contact us" etc.

I would like a menu bar at the top which links to different sections of the same page. When the user clicks "product" it should scroll down to that section. Also as the page scrolls the menu bar should be still available (frozen) for the user to jump to different sections.

I tried using the in-built menu offered by sitebuilder but I had two problems.
1. Menu items only link to other pages not anchors
2. Cannot freeze the menu bar.

Is there a built-in theme similar to such a design? If not how can I design such a website?

Any help is greatly appreciated.

Thanks