It's so easy. I just took one of the girl's old artwork and rolled it up into a cone. Then I taped it to keep it the right size cone. You don't want it to touch the bottom but you want a good seal around the jar so the flies won't get out.
Then just add some fruit cut up and a little fruit juice. I covered up my fruit bowl with a towel and shooing the flies off. Then, you just have to wait. It only took about 3 days to catch the first round.
And there you have it!