You cannot grate tomatoes. The skins are too tough. All you'll get is squashed tomatoes. Take some tomatoes. Put them in a saucepan. Cut them in pieces first, or mash them gently in the pan to release some juice. Cook at low to medium heat(tomatoes burn easily so watch them) until they are as soft as you want, mash them as small as you want. Along the way, the peels will come loose so you can remove them if you want. This will take a while, half an hour or so at least. You now have cooked tomatoes. If you want some seasoning, you could have cooked a little chopped onion or garlic along with those tomatoes. Both go well with tomatoes. You can add any vegetables you like, in fact, and any seasoning. Salt is pretty basic, Black pepper, oregano, basil, are all good with tomatoes. A touch of chili powder, maybe. A hint of cumin. A tiny tiny hint of cloves is interesting.
I know, that isn't a raw recipe. I think tomatoes are better cooked, even slightly. If you want a truly raw recipe, look up one for gazpacho. It might call for using a blender. You can chop finely instead, which is how people made stuff like that before we all had electricity. A sieve or food mill can also be used to puree things. You don't have to do much to get juice out of tomatoes. cut them or squash them, the juice will come out. Tomato juice like you buy in the store is made with cooked tomatoes, by the way. Some people think if they juice a tomato they'll get something like it, but they don't.
Stock is composed of the liquid that remains after you have cooked a number of ingredients together, usually for at least an hour, and I cook mine for at least 6 hours. Time develops flavour. It usually but not always includes meat, chicken, or fish. It can be made from vegetables alone. It's a good way to use up odds and ends which aren't in the best shape for eating on their own but aren't spoiled. You make the stock from them and toss them when the stock is done. It's usually used as a starting point for soup. You use it as the liquid in place of water, becaue stock has more flavour. I don't know but guess that it started when people had no refrigeration. You couldn't freeze your leftovers. It was eat them pretty soon or throw them away. So people tossed them in a big pot and cooked them until they became something else to eat.