If you are in windows, go to "users\appdata\roaming\.minecraft\" its in the bin folder. You will have to enable the showing of hidden folders. Also with the new launcher, you can go to options, click on the "location on disk" and you will be good to go.
No... you don't open the jar file or try to run it directly... that doesn't work. You download the installer from minecraft.net and it will run the jar file through security and stuff... you don't actually need to know where the jar file is... unless you are planning on editing it.. If you are trying to add new textures, most of them are placed in the textures folder (again, can be found using the in game menu), if you need to change files inside the jar file, use winrar... or just use the patcher tools... which all have tutorials packed with them.
Even worse for me. I used the advice and went to bin.
The only folder is called Native.
I have 4 Jar files that say I don't have access to them, to get an admin, although I AM my computer's admin :sleep.gif:
I also have 2 files that I don't know what to do with.