Improved version
You can use tcolorbox to design the notepads; the cork-board is simply an image in the background. In my example below I used the beamer class, but you can use the boxes with a suitable class/package for posters:
The code (since I optionally used the equal height group, the code must be run twice so the heights can be appropriately calculated):
\documentclass[twocolumn]{beamer}
\usepackage[most]{tcolorbox}
\usetikzlibrary{shadows,shapes.geometric}
\usepackage{lipsum}
\definecolor{mybrown}{RGB}{33,34,28}
\definecolor{myyellow}{RGB}{242,226,149}
\definecolor{mygreen}{RGB}{176,232,145}
\definecolor{myblue}{RGB}{61,139,189}
\definecolor{myorange}{RGB}{245,156,74}
\definecolor{mypurple}{RGB}{230,111,148}
\definecolor{myred}{RGB}{215,80,50}
\newtcolorbox{NotePad}[2][]{%
enhanced,
frame code=empty,
boxsep=0.5cm,
top=0.6cm,
interior code={
\fill[#2,drop shadow]
(interior.south west) {[rounded corners=1.5cm]--
(interior.south east)} --
(interior.north east) --
(interior.north west) --
cycle;
\fill[#2!80!black]
([shift={(-0.9cm,0.5ex)}]interior.south east) to[out=30,in=-70]
([shift={(-0.55cm,0.7cm)}]interior.south east) to[out=-10,in=220]
([shift={(-0.7ex,0.9cm)}]interior.south east) to[out=250,in=30]
cycle;
\fill[mybrown]
([yshift=-10pt]interior.north) circle [radius=0.23cm];
\fill[mybrown!40]
([yshift=-10pt]interior.north) circle [radius=0.175cm];
\node[
cylinder,
cylinder uses custom fill,
cylinder end fill=mybrown!60,
cylinder body fill=mybrown,
rotate=115,
minimum width=9pt,
minimum height=16pt
]
at ([shift={(-0.2pt,-9.8pt)}]interior.north) {};
},
#1
}
\setbeamertemplate{background canvas}{%
\includegraphics[width=\paperwidth,height=\paperheight]{corkboard}%
}
\begin{document}
\begin{frame}
\begin{columns}
\column{.5\textwidth}
\begin{NotePad}[width=\columnwidth,equal height group=A]{myyellow}
Some test text for this block
\end{NotePad}
\column{.5\textwidth}
\begin{NotePad}[width=\columnwidth,equal height group=A]{myblue}
Some test text for this block and some more text so it's a little longer
\end{NotePad}
\end{columns}
\begin{NotePad}[width=\textwidth]{mygreen}
Some test text for this block and some more text so it's a little longer
\end{NotePad}
\end{frame}
\begin{frame}
\begin{NotePad}[width=\textwidth]{myred}
Some test text for this block and some more text so it's a little longer
\end{NotePad}
\begin{columns}
\column{.5\textwidth}
\begin{NotePad}[width=\columnwidth,equal height group=B]{myorange}
Some test text for this block and here we add some more words for the notepad so it spans several lines
\end{NotePad}
\column{.5\textwidth}
\begin{NotePad}[width=\columnwidth,equal height group=B]{mypurple}
Some test text for this block and some more text so it's a little longer
\end{NotePad}
\end{columns}
\end{frame}
\end{document}
A simple proof of concept:
The corkboard is just a background image (I used some random image I found at publicdomainpictures.net). The notepads are easily produced using TikZ through a command
\NotePad[<pin angle>]{<color>}{<text>}
The code:
\documentclass[varwidth=100cm,border=30pt]{standalone}
\usepackage{tikz}
\usetikzlibrary{shadows,shapes.geometric}
\usepackage{lipsum}
\definecolor{mybrown}{RGB}{33,34,28}
\definecolor{myyellow}{RGB}{242,226,149}
\definecolor{mygreen}{RGB}{176,232,145}
\definecolor{myblue}{RGB}{61,139,189}
\definecolor{myorange}{RGB}{245,156,74}
\definecolor{mypurple}{RGB}{230,111,148}
\definecolor{myred}{RGB}{215,80,50}
\newcommand\NotePad[3][100]{%
\begin{tikzpicture}
\fill[#2,drop shadow]
(0,0) {[rounded corners=1.5cm]--
++(10,0)} --
++(0,10) --
++(-10,0) --
cycle;
\fill[#2!80!black]
(9,0) to[out=30,in=-70]
(9.35,0.75) to[out=-30,in=210]
(10,1) to[out=240,in=30]
(9,0);
\fill[mybrown]
(5,9.5) circle [radius=0.25cm];
\fill[mybrown!40]
(5,9.5) circle [radius=0.20cm];
\node[
cylinder,
fill=mybrown,
rotate=#1,
minimum width=10pt,
minimum height=18pt
]
at (5,9.52) {};
\node[text width=9cm,minimum height=8cm] at (5,5)
{#3};
\end{tikzpicture}%
}
\begin{document}
\begin{tikzpicture}[overlay]
\node {\includegraphics[width=75cm]{corkboard}};
\end{tikzpicture}
\NotePad{myyellow}{Some test text}\quad
\NotePad[90]{mygreen}{Some test text}\quad
\NotePad[68]{myblue}{Some test text}\par\bigskip
\NotePad{myorange}{Some test text}\quad
\NotePad[90]{mypurple}{Some test text}\quad
\NotePad[68]{myred}{Some test text}
\end{document}
LaTeX can't handle spaces in filenames, so using appropriate filenames should solve your problem. Below is a more minimal example based on your code.
\documentclass[a0,landscape]{a0poster}
\usepackage{amsfonts, amsmath, amsthm, amssymb} % For math fonts, symbols and environments
\usepackage{tikz}
\usetikzlibrary{decorations.pathreplacing}
\providecommand{\SL}{\operatorname{SL}}
\newcommand{\F}{\mathcal{F}}
\newcommand{\Z}{\mathbb{Z}}
\DeclareMathOperator{\im}{Im}
\DeclareMathOperator{\re}{Re}
\begin{document}
%some written text here
\section*{Preliminaries}
%more text
Under the action of $ \SL_2(\Z) $ (or $ \Gamma_0(N) $) we can define the fundamental domain $ \F $ (or $ \F_N $) to be the set of all equivalence classes in the quotient.
\begin{minipage}{\linewidth}
\includegraphics{example-image-a}
\includegraphics{example-image-b}
\end{minipage}
%text, below is the tikz code that will not appear
\begin{figure}[h]
\centering
\begin{tikzpicture}[x=5cm,y=.3cm]
\draw[black, thick] (-.5, 24/pi+1.25) -- (.5, 24/pi+1.25)node[right] {$\im(z)=\frac{24}{\pi}+c_n^{-\frac{1}{176}}$};
\draw[black, thick] (-.5, 24/pi+4.75) -- (.5, 24/pi+4.75)node[right] {$\im(z)=\frac{24}{\pi}+c_n^{-\frac{1}{240}}$};
\draw[black, thick] (-.5, 30.5) -- (.5, 30.5)node[right] {$\im(z)=\frac{\sqrt{c_n}}{12}$};
\end{tikzpicture}
%\caption{}
\end{figure}
\end{document}
Best Answer
The
\begin{poster}command has a second argument that is the left column and can be used for such a logo. It is the{}just before the comment "TITLE AND AUTHOR NAME" in the sample tex file. Here is an example using that argument in the standard sample document, see the line with the comment%%%Added left logo. I have scaled down the logo's a bit more so that is enough space.