The package bases on the seminar class. For documentation about this class see its user manual.
An example:
%\documentclass[a4,dvips,portrait]{seminar}
%\documentclass[a4,dvips,semcolor]{seminar}
\documentclass[a4,dvips]{seminar}
\usepackage{kthslides}
%\twoup % for printing two slides on a page
% use the command 'markright' to define the occasion and the date of the
% slides' usage as well as the author. Ex.:
% \markright{\tiny SSAB 96, February 1996, (C) Carsten G. Br\"autigam}
%
% Alternatively use the command \pagestyle{KTHempty} to suppress
% all page numbering and references to the author/event etc.
% Note: This is against the KTH rules 'Vår visuella identitet' (1993)
%
\begin{document}
\begin{slide} % for landscape slides
\KTHhead{text of the headline} % optional command, use it if you want
\shead{text of subheader} % optional command, use it if you want
Y O U R T E X T
\end{slide}
\begin{note} % if you have comments on the previous
Some notes % slide, use the 'note' environment
\end{note}
\begin{slide*} % for portrait slides
\end{slides*}
\end{document}
Use the class option portrait when you have mainly slides in portrait orientation. Use the class option semcolor or semrot when you have slides in portrait and landscape orientation. Then slides will be rotated and printed correctly. For more help see SEMINAR user manual.