Documentation for ha cards

[FredrikM97]

Hi! I am building a custom card but find it very difficult to adapt to the ha cards component due to difficulty to find documentation. I have got it to work with ha-buttons etc but it was not without difficulty. Example the lazy loading caused a lot of issue to get testing up and running.

Now I am stuck at a new point where I try to use the ha-data-table but can't figure out how to integrate it and why only the + is visible for me.

Can anyone lead me on right path to utalize the ha components or is digging the code base the only approach?