Question with Minecraft Modding.?

So I downloaded WinRAR, opened my minecraft with that and i tried to delete the meta inf file. I had to repair the files and it made rebuild.minecraft. I opened that with WinRAR and then deleted the meta inf file, i then dragged my minecraft mod and modloader into it, from the files into the open rebuilt.minecraft.exe winrar window. When i try to use the application the computer says it is a corrupted .jar file. HOW DO I GET IT TO RUN WITH THE MOD I JUSS WANNA PLAY YO!!