I released my mod the Coffee and Tea Mod a few months ago. And I am currently working on an update to the mod right now. The Tea Mod adds Coffee and Tea Bushes, but I want to figure out how to have spawn them radomly in specific biomes naturally. However, I have never done any Terrain Generation before so I do not really no where to start. Any advice or help would be greatly appreciated.

Make a class that implements IWorldGenerator. In the generate() method, include a switch statement for world.provider.dimensionId. There are plenty of tutorials for this online. In your overworld generation method, just follow an ore generation tutorial, but instead of WorldGenMinable, use WorldGenFlowers.

That worked and with some tweaking I managed to get a result that I was pleased with. If anyone would like to see my code it's available here:

https://www.github.com/RichardsProjects/Richard-s-Coffee-And-Tea-Mod