it explains the procedure.
http://support.apple.com/kb/HT3819
P
I just turned on home sharing so I can have the songs I put on my laptop on my computer. So now what? When I click on home sharing now I get two choices, I can either turn off home sharing or I can choose photos to share with Apple TV. Why the heck isn't there an import songs from other computer option and how do I do that?
The songs are there because I had managed to get them before. But Then I put in a CD and put that on and now the only songs here are the ones from that one CD and the original instructions don't work. There is no library pop up menu

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