My two cents about horse manure: I introduced some into my very well-kept raised beds one year, and weed seeds from the manure turned it into a huge mess. (Keep in mind - my raised beds have zero weeds in them, though)
Anyway, I would opt for hot-composting the manure before adding to the garden.

EG

Razorbackfanok, I know exactly how you feel. Being raised in a town I always thought food came from the store. I have had a few gardens in different locales of Oklahoma always with different results. I proved to myself that I wasn't savvy enough to use those NPK chemical fertilizers , so I tried organic and still couldn't piece it all together the way I wanted to . Then I found a book on the internet about 3 years ago called The Ideal Soil ,I ordered it , read it , thought about my past gardens and now think I might be seeing the light at the end of the tunnel. I live 25 miles south of OKC and have sand that is 4 feet deep, black high calcium silt at the creek , and red clay that turns to rock in a couple of inches . In my way of thinking , there is no way of knowing what steps need to be taken to get your soil ready for spring without a soil test . If your garden spot has never been farmed , it is probably lacking phosphate and potassium but only a soil test will tell. If your goal at the moment is solely to put some garden produce on the table , I would look for dark brown to black earthy smelling soil ,dig a hole out the size of a 5 gallon bucket , mix in a cup of cotton seed meal or a cup of rabbit feed type alfalfa pellets , a couple gallons of finely shredded oak leaves or wheat straw , fill the hole back up , sprinkle some high calcium lime on top ,water well , cover up with plastic , cover that with soil to keep plastic down , and wait for spring. Now that may sound like a lot of work for one plant but that's the kind of work that I enjoy doing . I guess its one of those To each their own type deals . Whatever you do , its better than doing nothing . Just having the desire makes you half way there.

I wouldn't use fresh horse manure in spring. But if it possible, you can buy compost(probably by truckload, depending on the size of the garden it is much cheaper) and still do your garden next spring - just start as much early as you can, to let soil settle before you plant.

From what I've heard at two different farms in my area, but not from my own personal experience, is that adding the horse manure directly to the garden is too harsh for plants early the following season. Is there a spot you can let the manure compost before adding it to the garden?

Another method you can try, and this is what I do in my own garden, is leaf/kitchen composting. With enough turning and watering, it will turn to garden-ready soil in weeks, and should not be potent enough to burn your plants, at all.