Hi !
How can I use n8n ?
The short 3min video demo seem pretty cool but I don’t know how to have the interface in my browther 
That depends if you have already Node.js or Docker installed on your computer.
If you have Node.js installed you can start n8n like this:
# Take n8n for a spin without installing it
npx n8n
# or install it globally and then start
npm install n8n -g
n8n
In case you have Docker this:
docker run -it --rm \
--name n8n \
-p 5678:5678 \
-v ~/.n8n:/root/.n8n \
n8nio/n8n
If none of the above is the case and you are also not a technical person you can write an email to hosting@n8n.io to inquire about the hosted version.