Preheat oven to 400-450 F depending on your oven, once you have made these a few times you will work out the best temperature.
Poor the dripping into your yorkshire tray, a muffin or cupcake tray would probably work too and place in the oven to get the oil nice and hot.
Take the oil out of the oven and spoon a couple of tablespoons into each section of your pan.
Place back in the oven and cook for 20 minutes or so. Do not open the oven once added, this is very important, if you don't leave them alone you will get flat doughy puddings.