symbolic toolbox installation

i work under windows(window 7 ultimate)
I have already installed maxima perl in my system as given in the follow link:-

http://spoken-tutorial.org/wiki/index.php/Scilab_Symbolic_Toolbox-English

the problem now is i am not able to  edit the serveur.sce file (we need to change here the version of maxima to 5.20.1) ,how and where i exactly have to edit this serveur.sce code

error during execution of this code is

 SYMBOLIC TOOLBOX ERROR: Maxima is not in your path or is not insta       lled                                                            If Maxima is installed add its path in the following file:     serveur.sce  

Thanks