1. Download and install Forge:

You can download it here

Now you should see a new installation in your minecraft launcher with the Forge logo

3. Download Open Terrain Generator

You can find the downloads at the bottom of this page

3. Download a biome pack

We will download Biome Bundle by mc_pitman, you can download it here

3. Put both Open Terrain Generator and the biome pack in your mods folder

a) Go to AppData\Roaming\.minecraft\mods
b) Drag the downloaded files into the mods folder

4. Play minecraft using the Forge installation

5. Once you are in the game:

a) Create a new world
b) Select OTG world in the world creation settings

6. Have amazing adventures

Open Terrain Generator Mod