The easiest way to do this is to connect your MacBook Pro to your iMac, and use
Migration Assistant to move all your stuff over for you. This is the official Apple way to move your stuff over.
If you want to still use your iPod to do that, it's a lot more complicated and will probably require you buying some software to do so. Just Google search, "get music off iPod" and I'm sure they'll be options out there.