ITunes library file

I have just turned to an Mac user from a low time PC user. Here's the issue. I got the new iMac(wifi) and I have a Netgear ReadyNAS Duo(Ethernet). I stream my music from my NAS. On my PC it was network mapped m:\media\iTunes\Music. I tried to import my library to my new mac. iTunes Library.itl so I dragged it into iTunes it picked up my apps but not my music. Before on PC I could add the library use shift when open iTunes to select the library but its not pickling it up on my mac is there anyway to select the library on start of iTunes and select the library.

I'll let you know how that goes!