Hello,
Exporting images created with tikz to html.files seems a complicated task.
This file is corrected exported into pdf:
#+OPTIONS: LaTeX:verbatim
#+OPTIONS: tex:imagemagick
#+LaTeX_CLASS: article
#+LaTeX_CLASS_OPTIONS: [koma,a4paper,11pt]
#+LaTeX_CLASS_OPTIONS: [times]
#+LaTeX_HEADER: \usepackage{tikz}
#+LANGUAGE: en
#+OPTIONS: ':t
#+OPTIONS: tex:t
* Tikz test
Here's a tree, exported to both html and pdf.
#+begin_src latex
\usetikzlibrary{trees}
\begin{tikzpicture}
\node [circle, draw, fill=red!20] at (0,0) {1}
child { node [circle, draw, fill=blue!30] {2}
child { node [circle, draw, fill=green!30] {3} }
child { node [circle, draw, fill=yellow!30] {4} }};
\end{tikzpicture}
#+end_src
But I do not succeed to export it into a html file.