Their are several articles on www.ni.com that address multithreading. Simply goto www.ni.com and do a search for "multithreading". Many articles will be found.
Their is also the LabWindows/CVI Basics II Course Manual, which has a section and several excercises on multithreading. National Instruments runs this course both in Austin, TX and at various onsite locations throughout the year. Also, a course kit (manual, exercises, and solutions) can be purchased from www.ni.com. For more info about these courses, follow www.ni.com >> Products and Services >> Services and Training".