Most of us got our hair tested through Analytical Research Labs. http://www.arltma.com
They have many good articles on their website.
There is also Trace Elements Lab. Both of these labs would be recommended by those of us here.
If you are from Canada, ARL may work directly with you. This is what I do. Otherwise you will have to contact the labs and they will send you a list of practitioners to start working with.
Once you get your report your practitioner will put you on a supplement program and diet.