Q: I used MIgration Asst to move by wifi the contents of my MacBook (2008) 10.5.8 to new MacBook Air (Mavericks 10.9.1); it transferred as a separate user. I had wanted to merge and then delete unwanted files. How??

I used MIgration Asst to move by wifi the contents of my MacBook (2008) OS 10.5.8 to my new MacBook Air (Mavericks 10.9.1); it transferred as a separate user. I had wanted to bring over documents, photos, home videos, etc, but not separate from my admin/user identity on the new one. Instead I have to log in to each, and the MS Office apps didn't migrate with it, so I've had to re-purchase MS 365 to open docs from work.  I don't want two separate Mail files running identically, etc. in the two user ids.  How can I merge simply to have my documents and photos, etc.?  I've now found info that says my old computer was too old for the Migr. Asst. and that I needed top copy material.  How do I undo what I did wrong and get it right?