How can I make a similar table as the below image with a sidebar pointing to some rows is the table?

My attempt to create something similar
\documentclass[12pt]{article}
\usepackage{color, colortbl}
\usepackage{tikz}
\usetikzlibrary{tikzmark, positioning, fit, shapes.misc}
\usetikzlibrary{decorations.pathreplacing, calc}
\begin{document}
\begin{table}[!ht]
\caption{HMM}\label{tab1}
\centering
\scriptsize
\begin{tabular}{|c|c|c|}
\hline\\[-1.5ex]
blablablabla & blablablabla & blablablabla \\[0.5ex]
\hline\\[-1.5ex]
blabla& blabla & blabla\tikzmark{a}\\[0.5ex]
\hline
blabla& blabla & blabla \\[0.5ex]
\hline
blabla& blabla & blabla \\[0.5ex]
\hline
blabla& blabla & blabla \tikzmark{b}\\[0.5ex]
\hline
\end{tabular}
\begin{tikzpicture}[remember picture, overlay]
\draw[very thick] ($(pic cs:a) + (2.5em,0)$) -| ($(pic cs:a) + (4.5em,0)$) -- ($(pic cs:b) + (5em,0)$) -- ($(pic cs:b) + (3em,0)$) --($(pic cs:a) + (2.5em,0)$);
\end{tikzpicture}
\end{table}
\end{document}

\documentclass{...}and ending with\end{document}.• Note this is a Q&A site, not a please do this for me service. What do you have so far.
– albert Aug 16 '19 at 14:51