In general just doing basic grounding and centering should help. If you have one particular chakra that seems to be working more so, than any of the others, then a good balancing should be enough to put them all back on an even track.
This is a good
balancing exercise, and though it's primarily geared towards opening, or removing blockages, however it can be used to help calm them a bit as well. When you are bringing the light up through your chakras, and you visualize the rotation, use your breathing to slow down the rotation - if it's overstimulated, it will likely be spinning a bit faster, so just continue to hold the pattern, taking slow, deep breaths, until it slows to match your breathing.
Her site has some basic Chakra information - however I would highly suggest getting the book "Wheels of Life" by Anodea Judith. Definitely would have more of the information that you are looking for.