Google wifi antenna boosters and then start checking out Craigslist or Ebay for a used rooftop sat receiver.

You don't use a normal Yagi antenna; you have to have a parabolic reflector going into a klystron tube. Or in other words: You need a used sat dish like Dish Network or Direct TV uses.

It all looks rather easy, but check out the You Tube videos on this subject and see what you think about them.