No problem!  The template is still pretty much an ongoing experiment, and we're working on trying to make it a little simpler and user-friendly, and to improve the instructions that show up above the edit window right now.  If you have any thoughts on what works and what is confusing, or ideas about what might make it easier to use, please don't hesitate to either leave me a message, or comment at Template talk:DYKsuggestion, where there are several ongoing discussions about how to improve the template.  
For a quick answer to the problems you were having: the fields such as  and  don't need any wiki markup such as brackets; the template puts that all in by itself.  So, for example, the exact code I used to make the template show up the way it does now is as follows:
{{subst:DYKsug
 | article=John Johnson (fur trader)
 | creator=Parkwells
 | hook =... that the fur trader '''[[John Johnston (fur trader)|John Johnston]]''' had such a large library in [[Sault Ste. Marie, Michigan]] that his children used it to learn about classic [[British]] authors?
}}
Hope this helps! — talk/contribs