Chicken manure is a "hot", high nitrogen fertilizer. Applied directly to plants it can burn them.
I find that a mix of chicken manure, horse manure, and bedding, allowed to rot for a year or so makes a great garden amendment. (Or if you turn it a few times it is ready in about six months.)
Another good way to use chicken manure is to add it to the general garden compost -- especially in the fall when the compost pile has a lot of "browns" (leaves, woody garden waste, etc). If you build a pile in the fall when you do your garden cleanup, make layers of browns, then chicken manure, a sprinkling of garden soil, soak well, then repeat. (You can alternate garden greens with the manure if you have extra greens and/or not enough manure.) The manure adds the nitrogen the pile needs to cook down quickly.
In the spring you might be able to get away with less-well-rotted chicken manure if you work it in a couple of weeks prior to planting, but I basically use the two methods above and capture the nitrogen from the chickens in my compost piles.