Masonry, Cardstack and Multiverse like themes setup

I am trying to make some themes like Masonry, Cardstack and Multiverse work, but it seems i am not getting something right.

When i create pages with articles and they work good with simple design themes like Editoria, Haywire, Medium, things are looking good. When i change to the ones i mentioned at the top i get nothing. I start to understand that there is something related to pages and their setup.

Can someone give me some directions to create my first post in one of these themes? (i.e. Masonry) and i will be able to replicate the same thing to the rest. I just need to figure out how i create the first post.

Thank you in advance for your help