How does a timeshare work 10pts?

So here is the thing, Im getting married on May 29, 2010. I have a co-worker who owns a time share and is willing to give me her bonus week to use in cancun. Which does not cover airfare, food and drinks... Only the stay. We are planing to stay at Sun Palace Resort which is all inclusive, but what does that mean? Since the time share only covers for the stay will the all inclusive would still apply to us? is that an additional charge for all inclusive? I really don't know how these time share works... a little help clarifying this please???