Drill 2 6mm holes in the lid of a jam jar, poke air line into one hole to the bottom of the jar. Dont use an airstone!!! add aquarium salt at 35 grams per litre to a litre of water and fill bottle to 1 inch from top, add shrimp eggs and turn on air pump. You will have baby brine shrimp in about 24-36 hours. There are plenty of DIY sites with them on too.
Good Instructions are here too, this one uses jam jars too