tikz_demo.tex

\documentclass{article}

\usepackage{tikz}
\usetikzlibrary{calc}

\begin{document}

\begin{tikzpicture}
    \draw (0,0) -- (2,2);
    \node (first_node) at (2,1) [draw, fill=red!20] {\(x^2\)};
    \node (second_node) at ($(first_node) + (4, -4)$) [draw, fill=blue!20] {This is a sentence};
    \draw [->, green!67] (first_node) edge [out=0, in=90] (second_node);
\end{tikzpicture}

\end{document}