Advice re manure

I have plenty of well rotted horse manure and wanted advice re using it. I am growing veg in containers and if I'm right from reading the threads I shouldn't manure the carrots - is that right?
What about potatoes and onions? Do I mix the compost with the manure or I do the lay the manure in the bottom of the containers.
Many thanks  

You are right about the carrots same with other root crops. parsnips etc don’t manure.