This video may be dated, but you can get an idea of how botox is administered. Dr. Silberstein who is interviewed for this video has been my doctor for over two years. Unfortunately for me, my migraines did not respond to the treatment. But, that doesn't mean that others cannot benefit.
If the flash video above doesn't work, try the link below
http://www.5min.com/Video/Treating-Migraines-with-Botox-175530369