promotions

Is there a 'good' video on how to set up promotions in SL. I been playing in the corporate program, added a corporate mechanize but I don't see it when I try to build the promotion. I only see the rent. That's the other thing, for some stupid reason I can't create a promotion with two rent types. I wanted to use the senior discount along with the another rent discount but it won't let me. I'm trying to offer 6 months at a percentage off and for seniors a discount that will never expire. Perhaps, I'm asking for too much!!