having macbook find my itunes folder/music on my external hard drive

short story/question:

my itunes library with all my music (1000+ songs, and iphotos) is on one of those external harddrive firelite things. how do i set up my macbook to search for the itunes library on my external harddrive, rather defaulting to an itunes library mistakenly loaded on my computer?

long story: (bare with me, because i'm in a panic stress mode without my music)-

my kids both have macbooks. my daugther made a video that was on a flashdrive. she couldn't get the flashdrive to open the video on her macbook. unbeknownst (?word) to me, she inserted her flashdrive into my macbook. my external harddrive, with all my music on it was NOT hooked into my macbook at the time.

when she inserted the the flashdrive, the macbook said something like "can't find itunes, would you like to choose an itunes folder?" i still didn't realize she was using my macbook, so i clicked on "choose a folder". now i get a little confused, but two folders came up, the first was labled "itunes", i believe that was an old folder we (apple geniuses) had labled as the orginial music in my library for my external harddrive. there was also a second folder i remember creating labled, itunes1 (or something), which i believe was an updated copy of the most recent music on my external harddrive. i had to give the folder a different name otherwise it wouldn't accept the music again. i thought i deleted the original folder though, after i made a copy of the most recent music. i'm digressing though, sorry.

anyway, i chose the first itunes folder, and her flashdrive video didn't open, so i clicked on the second folder. her video opened up. she was happy. she removed the flashdrive (the wrong way, by just pulling it out. then inserted it again, and removed it correctly.

as she went to shut down the computer, i realized she was using MINE rather than hers or her brother's. i flipped, because know i realized i somehow download some form of origin itunes setup directly onto my macbook.

i inserted my external harddrive with my music, and needless to say, it couldn't find my music. i double clicked on the external harddrive to try to find or open the music... nothing. i find it hard to believe that i lost my music off my external harddrive, considering it was never connected in the first place.

other issue- i recently downloaded some music (from a grateful dead website) not off itunes (which i rarely if ever do). when i clicked on "a button" in itunes, it seemed to download just that music into, i believe the itunes on my macbook. (that music was also in my external harddrive).

bottom line:

how do i get my macbook to search for my intues folder/music that was on my external harddrive, rather than on the macbook itself? i think the macbook needs to know to search the external hardrive, rather than the macbook itself.

i have an appointment with the apple genius bar on saturday, but if someone thinks there's a simple solution that i can do (that will ALWAYS work to have my computer search my external harddrive, rather than the itunes folder on the macbook itselft). i'm willing to try.

my biggest fear... losing, or having lost ALL of my music and photos from the external harddrive.

btw: i hopefully have most of that music backed up to a SECOND external harddrive. which i bought just in case the first one crashed.

help. please. and thanks for listening.

not sure which macosx i have. i think it's 10.6.8, but it may be 10.6.7. i'm typing from work now.

thanks,

anthony