If you have some idea of programming methods and concepts, Mastering VBA for Office 2010 by Richard Mansfield steps through the syntax and gives an introduction to the "Object Model" for the main Office applications.

An older book is"Writing Word Macros" by Steve Roman, from O'Reilly. It is somewhat more oriented to the person familiar with Word.

One of the best resources for troubleshooting and particular questions is the MVP website.
Macros and VBA (Visual Basic for Applications)