After you have received the bag with eggs, they need to be put into water, the whole content. Best you provide a plastic or glass container with a volumn of about 1 litre. Water quality is crucial. You need to prepare water of about 200 microsiemens or if not available you can take pure osmosis water or even distilled water. Water from the tank is risky as there is a lot of micro fauna which can harm the eggs. A water level of about one inch or 3 centimetre is fine, so they can reach the surface for air immediately after they had hatched.
Cover tyhe container with a piece of cloth to prevent light, as the eggs are very light sensitive. After the first one has hatched uncover the container the other remaining eggs are developed that far that they are no longer light sensitive. No air bubbles, no heater, room temperature is fine if between 22 – 24 degrees. Be aware that they might hatch between 10 to 21 days, they do not hatch at the same time.
As a first food you need infusoria, paramecium or greenwater. Only after a week they are able to take brine shrimps. Feed twice a day small amounts. You can add some dried powder food which you get in certain shops.
As soon as they are 0.5 cm in size you can move them to the fish tank.