\documentclass{article}
\usepackage{lipsum}

\usepackage{color}
\usepackage{xcolor}

\usepackage{colortbl}

\begin{document}
\definecolor{Black}{cmyk}{0,0,0,1}
\definecolor{White}{rgb}{255,255,255}

%\begin{tabular}{lr}
%\rowcolor[Black] one & two\\
%\rowcolor[White] three four
%\end{tabular}

\colorbox{Black}{\textcolor{White}{This is something}}
\begin{tabular}{|l|c|}
 \rowcolor{violet}
 one&two\\
 \rowcolor{Black}
 three&four\\
\rowcolor{White}
five & six
 \end{tabular}

\end{document}