Get a paper towel and wrap your apple seeds in them. Wet the paper towel and put it in the plastic bag. Make sure the plastic bag is sealed tight, and put it in the fridge. Your seeds should take about a month to germinate but check every few weeks and wet again if dry. Your seeds will start to have little white sprouts coming out of them soon enough that's when you know there ready for planting.
Once the seeds have germinated just drop them into any pots about 1 - 2" deep and cover in good compost. Then just watch them grow.