Very short and easy. Simply go to "Learn the steps" from the main menu and there will be 4 sets of dances each with 4 "moves" once you get a check mark in each of the 4 steps under the "Cumbia" section this achivement will pop
The 4 steps are:Two Step
Forward and Back
you have unlimited attempts to complete the steps, if you are having trouble just change the speed to slow, (NOTE: you can only get the checkmark by doing the moves correctly on normal speed)
You know you have done well enough when you fill the bar in the bottom left corner to get a "Zumba" rating. once you get 5 of these the narrator girl will say something like "good job" or "how about trying another step?" you have completed this step at this point and should see a check in the selection menu like this:
Once you have the 4 steps checked the achivement will pop when you enter the selection screen. sorry my pic is a little blurry as I was trying to take the picture before it went away.