Q: Tikz to draw a figure I have problems drawing the following figure using TikZ. Can someone please help me? I'm trying it now for 2 hours :(
Thanks in advance!
So this is my code. I tried to rewrite another code but I think I failed

\documentclass[12pt]{article} 
\usepackage{tikz} 
\usetikzlibrary{positioning} 
\begin{document} 
\begin{tikzpicture}
[
  every node/.style=
  {
    minimum height={1.5cm},
    thick,
    align=center
  },
]

  \node[draw] (PS) {Potential\\bidder\\solicitation}; 
  \node[draw, right=of PS] (CA) {Confidentiality\\Agreements};
  \node[draw, right=of CA] (IB) {Informal\\Bidding};
  \node[draw, right=of IB] (FR) {Final\\Round};
  \node[draw, right=of FR] (TA) {Takeover\\agreement and\\announcement};
  \node[draw, right=of TA] (PB) {Publicbidding\\newtakeover\\agreement};

  \draw[->] (PS) -- (CA);
  \draw[->] (CA) -- (IB);
  \draw[->] (IB) -- (FR);
  \draw[->] (FR) -- (TA);
  \draw[->] (TA) --(PB);

\end{tikzpicture}

\end{document}


A: 
\documentclass[12pt]{article}
\usepackage[margin=20mm]{geometry} % added
\usepackage{tikz}
\usetikzlibrary{arrows.meta, % added
                chains,      % added
                decorations.pathreplacing, % added 
                calligraphy, % added, had to be after decorations.pathreplacing
                positioning}

\begin{document}
\begin{tikzpicture}
[
node distance = 7mm,
 start chain = going right,
  box/.style =
    {
    draw,
    minimum height={1.5cm},
    thick,
    rounded corners,
    align=flush center,
    font=\small,
    on chain,
    join=by Arrow
    },
 Arrow/.style = 
    {
    draw=gray, line width=2mm, -{Triangle[length=3mm, width=6mm]},
    shorten >=1mm, shorten <=1mm
    },
    BC/.style = 
    {
    decorate,
    decoration={calligraphic brace, amplitude=6pt,
    raise=2mm}
    very thick,
    pen colour={gray}
    },  
]
\begin{scope}[every node/.append style={box}]
  \node (PS) {Potential\\ Bidder\\ Solicitation};
  \node (CA) {Confidentiality\\ Agreements};
  \node (IB) {Informal\\ Bidding};
  \node (FR) {Final\\ Round};
  \node (TA) {Takeover\\ Agreement and\\ Announcement};
  \node (PB) {Publicbidding\\ Newtakeover\\ Agreement};
\end{scope}
%
\draw[BC] (PS.north west) -- node[above=4mm] {Private Takeover Stage} (FR.north east);
\draw[BC] (TA.north west) -- node[above=4mm] {Public Takeover Stage} (PB.north east);

\end{tikzpicture}

\end{document}

Note: your diagram is very wide, so probably you will have problems to fit it in text width. Maybe you can further reduce font size, for example from \small to \footnotesize.
Edit:
to MWE preamble are added comments to annotate added TikZ libraries and package (geometry). For positioning of nodes is used library chains and for arrows between them chains' macro join. For braces is used library calligraphy, which render nice braces (braces can be drawn with decorations.pathreplacing only too, for details see TikZ manual). 
