First time user .... PLEASE HELP

Hi everyone

Im creating this post in the hope that someone can help me. Previously I have used a family PC for my iTunesand sorting out my library but now I have upgraded and got myself a MacBook Pro but Im totally confused as to how to sync it and I want to have my MacBook Pro as my main recognised computer as the family computer has now been sold as well. What Im really confused is with the syncing of the librarys as when I plugged in my iPod I got a message telling me that I could only syncing to 1 library but how do I merge the tracks I currently have with on my iPod with the songs in the library I have on m MacBook Pro as I have some tracks and audio interviews on my iPod that I can't see in my library on my macbook Pro

I understand this is probably really easy to understand for some of you but I find this very difficult to understand as I get confused very easily

Many thanks for your help with this matter

Kindest Regards

Shaun