Q.Lemon Growing in the tropical rainforest zone
1) How can you grow lemons in the tropical rainforest zone?
2) If possible, how do you plant the seed?
3) Can you pant it in a garden and do you need to give it additional care?
4) What other fruits can you plant in this zone?

1. Lemons should do well in a tropical rainforest location. I couldn't find much information on growing lemons in truly tropical climates, but this article explains how to grow them in Florida (subtropical) but the information should be mostly the same:
http://edis.ifas.ufl.edu/hs402
2. and 3. Lemon seeds (either purchased or from a lemon you eat) can be planted in a small pot of soil. Keep the pot indoors and water it so that the soil never dries out until the seed germinates and the seedling begins to grow. When it gets bigger, you can plant it in a garden. This article gives more details:
https://www.gardeningknowhow.com/edible/fruits/lemons/propagating-lemon-seeds.htm
It should also be fertilized, but can do fine in gardens where there is high natural fertility. This article provides details:
http://hendry.ifas.ufl.edu/HCHortNews_CitrusFert.htm
4. Here is a list of tropical fruits that should do well in the tropical rainforest garden, and links to more articles about them:
https://www.gardeningknowhow.com/edible/fruits/fegen/growing-tropical-fruit-trees.htm
http://www.faculty.ucr.edu/~legneref/botany/trofruit.htm