migration issue

I have migrated from g4 17" mac to a new iMac running Mountain lion. Now I have two user accounts on my iMac. The first one I setup when i setup the imac originally yesterday. The other is my old user with lots of documents, apps etc. Now I am not clear on how to move the old into the new so I can delete the old user and be all setup. I just do not understand how to do this. I know you can't have both users on at one time. I am not clear how to use share if that is the way. One place mentioned share, user, home. As you can see I am totally confused.

You best bet is to continue using the old account that came across and delete the new one you set up yesterday

Is it possible for two different users on the same computer to access the same files? Example: I have made my wife her own user login, but her login cannot access the photos in my iPhoto app.

Sharing an iPhoto library between users: iPhoto: Sharing libraries among multiple users

Thanks

Larry H