In Mountain Lion your Library; which contains various useful folders such as your preferences, application support and many other files and folders, is hidden within Mountain Lion. This is not normally a problem since you really don’t use it that frequently. However, if you want to change a file, delete a preference and just see whats stored in there you need a method to get it back. This is a quick tip to show you how to do it.
Normally your Finder window doesn’t show your Library or the main system library.
To view it, in the menu bar go to Go > Go To Folder. Within the pop up box that appears type in ~/Library. The tilda (~) links to the current logged in users library. To view the main Library simply type /Library. When you press go a new Finder window will pop up with the folder you want.