I've been sent over $200 in cheques over the past two years - it's amazing! The app is the easiest way to use it because a small banner is at the top when you go to a store/site through the app. I screwed up once using my laptop/web browser because it jumped to another window and then I ordered through the non-ebates window by accident.
If you'd generally use your computer to order anything online, one trick is to fill your cart signed in on the manufacturer's website (i.e. Sportchek) close it and then go through the ebates app on your phone to that site and sign in - the ebates banner will be at the top of your phone screen and your cart should have your stuff in it still