Hopefully a very basic question.

My 7yo old daughter wanted to try and grow an apple tree from the seed in the apple she was eating. With guidance she put the seed and a wet paper towel in a ziplock and left it in the sun for a week.

The seed is sprouting. There are now two green pods the size of the original seed and a short white stalk.

Now we want to place it in a cup with dirt and see if it will grow.

Now my dumb question: What side goes up? What end is the beginning of roots and what end is the beginning of a tree trunk? I'm guessing the green pods go down and the white up but that is really just a guess? How deep in the soil should it be?

Any other advice to help her turn this into a tree?