Well, rather than "Begin at the beginning, and go on till you come to the end: then stop," as the King advised the White Rabbit in
Alice in Wonderland, with backward design, you think about where it is you want to end up, and make a plan for how you're going to get there.
So you ask yourself, "what do I want my students to have learned once this course/unit/chapter/etc. is finished?" Then you ask, "Okay. What can I do to measure how much of that they've learned?" You need to make your assessments match your learning goals.
Once you've done that, you make a plan for "teaching to the test," which in this case is a good thing, because you have a good test!
There's also lots of information and good linkage at the Understanding by Design wiki. You'll have to google it, because for some reason, when I try to post a link, it activates the spam filter.