Assuming you are in MAPDL, after you read in the curve fitting commands above, (make sure you are in the same directory that the file sample.exp is located in) you can open the curve fitter:
Main Menu=>Preprocessor=>Mat'l Properties=>Matl Models=>Structural=>Nonlinear=>Viscoelastic=>Prony Curve Fitting...
..and from there, choose the Curve fit labeled "test" (there is only one). Then click "Plot" to generate the resulting curve fit.
I cannot answer your second question.