you just put some of the composted manure in a cloth bag and steep it in water just like you would sun tea. Then you use it in the garden. I made compost tea last year but I can't say that I saw any improvement in my plants that got it compared to those that didn't so I stopped doing it.
Some suggest that along with the manure or compost that you add molasses. Don't unless you really want it to stink to high heaven.