Shane, there are 2 ways of making nettle or comfrey ‘tea’.
1) Cut your nettles or comfrey, put them into something like an old pillowcase so that you can take them out easily once everything has rotted down. Tie a knot in the pillowcase so nothing falls out and put it into a bucket or any sort of container that will hold water. Add water to cover your pillowcase and leave to ‘steep’ (you may want to add a lid because it gets stinky!) After 10 – 14 days or so, remove the pillowcase. Dilute with water as Rhys says and feed your veg with it.
2) 2nd method, cut your nettles or comfrey as before, pile them into a large plantpot, pack them in dry and weigh the leaves down with something heavy.
I also like to beat up my greens too, bruising them I feel, might get things going a bit quicker and I can pretend it’s someone who is not my favourite person.
Put your flower pot inside a bucket or anything that will hold water and leave it for the 10/14 ish days. Liquid will start to come out of your leaves, and into the outer bucket. Collect the liquid and dilute in the same way to feed your beans or whatever, good for tomatoes too.
The good thing about the dry method is that there is no smell at all, and believe you me comfrey or nettle tea really stinks when made with the 1st method.