Getting error: "Matrix do not have a method or closure named..."
On your screenshot of the block type powitanie you see two fields: powitanieNaglowek and powitanieTresc. Yet, in your code you try to use 

  &lt;h2&gt;{{ block.naglowekPowitanie }}&lt;/h2&gt;


The error simply says: in the block type you are using there is no field called naglowekPowitanie.

Changing that H2 to 

  &lt;h2&gt;{{ block.powitanieNaglowek }}&lt;/h2&gt;


should do the trick.