Complex data retrieval for Word Layout Templates ?

Hi guys!

I want to create a word template which will gather data from related entities.

I have a Contact entity where i have a subgrid with Open Cases. In my Cases there are the Service Activities (for that case for that customer). What i would like to do is to get information from the fields or grids from all three entities and use them to create a Word template layout.

Is there a way to do this? Can someone guide me through on how to do it. I followed this guide http://www.crmsoftwareblog.com/2016/12/word-document-templates-that-use-fetchxml-for-complex-data-retrieval/ but got stuck with the code. I don't know where to use the code.

Thanks a lot!