How to draw a choropleth (color coded map)
Select a variable from the top left part of the interface. Variables are organized hierarchically, and so the user must browse through the select boxes as if they were navigating folders. Upon selecting a variable, the variable will be downloaded and appear in the variable list just below.
Hover over the variable name, then click on the map icon to draw the choropleth map.
Configure the map options as desired and click "Update", or "Save As" to save it as a new style.
Be aware that when you use update, all maps that use the same style will use the new updated style as well. >> More on styles.