Simply place the bones or carcass into a pan large enough to hold them and cover with water
Add whatever you fancy for extra flavour (or leave as it is – the bones are tasty on their own!)
Bring to the boil and simmer for couple of hours with the lid just off
Once done, pour the stock through a sieve into a clean bowl to remove all the bits and pieces
If you have a large amount of stock you can pour it back into the pan and reduce it down by simmering it with the lid off for as long as it takes to reduce it to a more manageable amount
Poor it into whatever you have available for storage in the freezer or simply put it all into the fridge if you will use it within a few days
If you have reduced it down, when you’re ready to use it you can simply add more water to get the desired amount for your recipe (you don’t need to be too precise about how much stock or water you use as it just adds extra flavour and nutrients)