Multiple Users on the same Mac

[i robot]

Hi All

I have just set up multiple users on my iMac (wife and kids). I have tried multiple methods to share my itunes library with them but everything I googled seemed very complex and although i gave it a go it I couldn't get it to work. I ended up dragging my music to the user libraries (well one) from an alias I created in a shared folder to my wives itunes library. This seemed to work but I dont know if it will update as I purchase music on my itunes account and does use up disk space. I know I can share the library using fast user switching but I want them to be able to update their on music on their iPods/iPhone and this only allows them to listen. Is there a simple step by step instruction with out the jargon for Mac OS 10.5.3 on how to do this. Its not like I am trying to do anything illegal!

Thanks