How to change the distance between the title and the authors in the title page in foils?

Use vspace command in the author command. Example:

leftheader{textsc{Presentation using textsc{pdf}LaTeX, and FoilTeX, class}}
                                            %make a left header
%rightheader{textsf{thepage}}            %make a right header
MyLogo{Eugenia and Weiliang, UBC Stats}    %make a left footer
%rightfooter{}                             %make a right footer

title{shadowbox{Presentation using textsc{pdf}LaTeX, and FoilTeX, class}} % the document title

% the author
author{vspace{2cm}\r
         Latex Smart \r
         6356 Agricultural Road\r
         University of British Columbia\r
         Vancouver BC \r
         V6T 1Z2}

% the date
date{today}

begin{document}

thispagestyle{empty}

setcounter{page}{0}

maketitle