For more information, see the wiki of SpreadSheet WB.
The example proposes to draw a double rail whose number of holes adapts to its length.
In the first part you will see :
how to create a parameter table and how to drive a sketch from these parameters
(around the section of the double rail).
See definition of parameters.
In the second part you will see :
how to create parameter-driven PartDesign functions, then how to link parameters together
(creation of a hole and adaptation of the number of holes to the length of the rail).