If you are trying to access the Library folder in Apple’s new Mac OS X 10.7 Lion it’s been hidden. It’s now located in the go menu the trick is to hold the “alt/option” key while in the “Go” menu and it will appear.
I had split my original iWeb domain a few years ago & had got into the habit of creating a new domain for each site I design. However, after updating to OS X Lion “10.7” no matter which domain I double click on they all seem to just open the last site I was working on in Snow Leopard “10.6.8”
I will let you know if I find a work around but, if any one else has the answer I would be very grateful.