appletv can access a shared lib in itunes when the computer is running shared lib is turned on in itunes and the firewall and router is not set to block the ports required
if you mean connect to the appletv in terms of airplay mirror then your osx is too old and maybe your computer itself read here
I have just bought an Apple TV and have connected ti to my tv it has accepted my wifi connection I have done the sharing in my computer with i tunes but it will not let me connect to the apple tv on my tv help?
I'm confused? If you setup your ATV's wifi, then your tv connection works, since your tv displays the atv's settings? If you just cannot access your shared library, then double check you are using the same apple id on your atv as you have in itunes. Reboot both the atv and itunes.