Update 4 1 horizontal scalar field

4-1-horizontal-scalar-field.md

@@ -13,7 +13,8 @@ Open your data file(s), using buttons on the _Home_ menu category of _Menu Bar_.
 In order to visualize the distribution of the variable on a layer, you can either
 
 * click the _Add Horizontal Plane_ menu button on _Layer_ menu category, and select variable/area/level, and then click "OK", or 
-* select the temperature variable on the _Variables Pane_, and click 'OK' to add layer. 
+* right-click the temperature variable on the _Variables Pane_, select _Add Horizontal Plane'.
+* double-click the temperature variable on the _Variables Pane_, and click 'OK' to add layer. 
 
 _Rendering Pane_ will immediately display the distribution, and a new layer will be added to the _Layers Pane_.