Hello @DirkTim,
Not anything related to this directly, but it might be a good start (if you are new to Silverfin Templating Language) to have a look at our slides we give during our free workshops (given each quarter at Silverfin HQ) : you can find that here
Also, be sure to follow the general rules as explained here please 
I wish you all the best with learning to make templates.
Regards,
Sven