No such thing as a jarmods or coremods folder in 1.6.4; just put it in your mods folder. Also, unless you absolutely MUST have Optifine to even run the game at a FPS higher than 5, it is highly recommended not to use Optifine, as its rendering method causes conflicts with many Forge mods, and if you ever experience any crashes/issues, our first response will be "remove Optifine and see if that fixes it".
