After the program is downloaded, start it up and make sure everything works.Download the one titled 'Eclipse IDE for Java Developers'. There are two different downloadable eclipses. Make sure to download the IDE for Java Developers which can be found here. The first step to set up is to, you guessed it, download Eclipse.
Also, this tutorial is based on Windows 8 and 10, but Windows Vista and 7 should be almost identical in structure. I will be showing you how to set up Eclipse to make 1.8 mods. It is easy to use and can support several different programming languages with a plugin or two. Eclipse is a free, donatable Integrated Development Environment (IDE).