Well, first, visit the Tree Management Merchant in the city and buy some seeds and saplings.
The plant the seeds in the specified area of village, when you're planting seeds, there is a progress bar.
When you want to plant saplings, it's the same.
When the trees are ripe, you can get a lot of rich fruit, not only yourself can use the fruit, but also it can be exchanged to game gold. This is one of the ways to make money in game.