Roughly chop the rest of your veg and put in the SC with the carcass.
Cover with as much water as it needs to have everything submerged, season with salt if you use it, I do.
Leave it on low overnight or for 6-8 hours and then once cooled, strain it through a colander then a sieve. The liquid is your stock which you can freeze or pop in the fridge for a few days. Use it whenever recipes as for stock and it is so nice!