Q: whAT ARE THE steps of the 3 week beach body workout?

A: Sorry, there's no such thing as an effective 3-week workout program. Best an average person can realistically hope for in 3 weeks is lose maybe 6 pounds of fat max at the expense of additional muscle mass lost (which increases likelyhood of fat returning later). My recommendation would be to lose only 3-4 pounds in 3 weeks which would ensure that you lose little or no muscle which would in turn ensure that the fat and weight doesn't come back.

If all you really care about is looking good for a few days in 3 weeks time and you don't care about the weight coming back later, then basically you should eat little, do a lot of running or other cardio and some weightlifting. This is NOT particularly healthy and will NOT give lasting results, but it will come as close as you can hope to your short-term goal.