The video tutorials and exercises at Academy X are not enough …
Hey Filipa,
Maria here from the X team. I suggest joining one of our live intro webinars (run every 2 weeks). One of our product managers walks through the basics of structuring a site, using CSS grid and other flex layouts. You’ll also have a chance to ask questions.
You can sign up to any of the dates here:
The next one is on April 14 
Webinars is the best!
There are also some tutorials on YouTube:
https://www.youtube.com/watch?v=iHEB5VO-ZMI
https://www.youtube.com/watch?v=DPiwMHMvZPQ&t=1s
https://www.youtube.com/watch?v=yDYrGP9UN3I
https://www.youtube.com/watch?v=DXxJMKQh7b8