Download resource(src) recommended http://files.minecraftforge.net/
Download eclipse luna
To install this source code for development purposes, extract this zip file.
cd forge_folder_xx
touch gradle.properties
echo "org.gradle.jvmargs=-Xmx1024M" >> gradle.properties
./gradlew setupDecompWorkspace --refresh-dependencies
./gradlew setupDevWorkspace
./gradlew eclipse
follow the setup video here:
http://www.wuppy29.com/minecraft/modding-tutorials/forge-modding-1-7/#sthash.bDafYKI0.cC3q7RTG.dpbs