Eclipse

Create a new project, and call it whatever you want. Next, create a package, and call it whatever you want. If you are using Eclipse to make a mod, you need to edit your build path. Right-click your project folder, click Build Path, then select Configure Build Path. If you are not already in the Libraries Tab, select Libraries, and Click Add External JARs... on the right. Next, you need to locate the directory where you saved our game. If you ever move this jar, you will need to repeat this process. After you have selected your jar and added it, you can now hit Apply and Close at the bottom.

You are now ready to make your mod.

NetBeans

We don't know.

IntelliJ

We also don't know.