Here are a few resources from Developer Zone that may help:
Building Multithreading Applications with LabWindows/CVI
http://zone.ni.com/devzone/conceptd.nsf/2d17d611efb58b22862567a9006ffe76/785199275fc420218625686900732df3?OpenDocument
Easy Multithreading Programming in LabWindows/CVI
http://zone.ni.com/devzone/learningcenter.nsf/03f7c60f17aad210862567a90054a26c/8829ce1ce5a4a9718625693800549f58?OpenDocument
The Knowledge Base has this article:
General Information on Multithreading for C programmers
http://digital.ni.com/public.nsf/3efedde4322fef19862567740067f3cc/6eccbaa87476eb22862568950071ccd6?OpenDocument
There are also some samples that ship with CVI. Look in the directory where CVI is installed and look under samples\utility\Threading.