The process for installing NEI has changed. (For the easier AGAIN!).
Install FML OR MinecraftForge into the jar.
Install CodeChickenCore into the coremods folder.
Install NEI into the coremods folder
i DON'T UNDERSTAND where is the core mods folder i heard you use forge that make this a forge mod and
i fu**cking hate forge
If you go into windows exporer, if you use windows, or something similar for another OS, and take a peek into the .minecraft folder, you'll see the coremods folder. THAT's where you put the jar files. Simple. And, you don't need forge unless you want to see the mob spawners. And you can't use mob spawners during regular game play, they only can be placed while in creative mode.