KevinCliffordI just need help for that.

1: locate your minecraft folder User/Library/application support/minecraft.

2: go into bin.

3: Rename Minecraft.jar to minecraft.jar.zip it should turn into a zip.

4: Open it.

5: Open the File called minecraft.jar

6: Copy everything in the Forge file (command A then command c).

7: Paste Everything into minecraft.jar (command V)

8: Click apply to all and replace.

9: Check if minecraft works and you are done!

Tell me if anything went wrong

It's hard. You need to get a zip program that doesn't suck. For some reason, OSX hates zip files. I couldn't figure it out, myself. I just installed the mod on a handy-dandy linux machine and then copied the jar file back to the mac.