Here is goldfish breeding, step by step:
1. Female becomes filled with eggs.
2. Males will compete to breed with the female and chase it around the tank.
3. A dominant male will succeed and start pushing on the female to release its eggs.
4. The female will give and release a few hundred eggs, at which point the male will release its sperm or "milt".
5. Smaller less dominant fish my end up eating the eggs as they fall out.
6. The eggs will be scattered throughout the tank in huge amounts.
7. The eggs will hatch in 24-36 hours. You should remove the eggs in this time period to hatch in another place.
8. The fry (baby fish) will me minuscule and open to predation.
9. The fry should be fed infusoria and rotifers or whatever commercially prepared fish foods you can find. (crushed fish flake will do). HOWEVER do not feed until the fish are free swimming. When they first hatch they won't be able to swim for at least a day as they absorb their yolk sacs. Feeding too soon will lead to fungus and death.
After a month they should be big enough to hold their own.
Your eggs and fry will always need to have water circulated over them to keep them alive.