Different colors

We imported our calendar from Yahoo. In yahoo, we had my entries, my wife's entries, and family entries. Each of the 3 was assigned a specific color so when you look at he calendar you can easily see who has appoitments. Can I do this with One Calendar? If so, how do I do it? Can I change all the imported entries for her at one time? Also, I imported all calendars from yahoo including holidays. How do I remove all holidays? Respectfully..