Of course such a thing is doable, but without knowing a little bit more about your document and what is being completed, it is difficult to advise.
At its simplest you could use Content Controls with explanatory prompt texts, which don't require VBA. At the other end of the scale you could have userforms to collect the data to be written to the document and put help texts there - see for example how the help is used in
http://www.gmayor.com/load_word_addins.htm