I may be wrong but I think that the IMAQ find pattern tool is not appropriate for a face recognition problem. If you are not a wizard of neuron networks or multivariate data analysis (chemometrics), I think you better forget it, and turn toward a ready-to-use solution.
Just to give you a superficial glance to the problem, you could read the very basic introduction
here.
CC
Chilly Charly (aka CC)