How to create a one page website

I’m building a website for the first time. I’m using the Sidney thema.
I created a number of pages but now I want to show them as a one page website.
Could anyone please instruct me which steps I have to take?
At the moment I only have my homepage hanging under the header.

Thanks in advance,

Hello Harald,

To help you getting started by replicating our main homepage demo, you can follow this tutorial: