This guide set your programming environment for developing JuicyRaspberryPie mod for Minecraft Forge.
Download installer from: http://files.minecraftforge.net/
Double click and run downloaded jar file, keep "Install Client" selection, and click "OK".
Open View -> "Tool Windows" -> Gradle.
In Gradle window, click forge -> tasks -> build -> jar to build output jar file.
The jar file is located in build/libs folder. Move it to mods/ folder of Minecraft.