There are resources all over the place online so I wouldn't consider buying a book for vba unless you can only work that way.
I would start with
Word Macros and Visual Basic for Applications (VBA) FAQ and spend some time looking at youtube videos - maybe a search like "Word vba tutorial" to get a feel for it.
You can record some macros and examine the code.
Then review the threads in this forum for questions that pique your interest and test the code by stepping through it line by line.
None of the effort will be wasted if you become more and more comfortable with dabbling with the code you see. Try to understand what each line of code is doing by stepping through code one line at a time.
Finally, when you want to address issues that you encounter, post your code and a sample document on a forum like this and people will give you a hand to get past the sticking points.