First put some fresh soil in a pot then put a seed in and let it have some sun and water. Next just the root will come out of the seed. The root will grow down because it needs to soak up water. Then the seed leaf will come out of the seed. When the seed leaf has come out of the ground the leaves will catch sunlight and air. After I a while some flowers will grow or the plant. Last the flower will turn into a pea pod or a fruit and there will be a seed ready in those plants to be planted and grow again.
The inside of a seed is called the endosperm. The endosperm is made of oils, sugars and protein.
No matter what the leaves will follow the sun. It is sort of like a magnet. The biggest seed is a coconut seed. Some plants do not grow from seeds, they grow from spores.