Install Raspberian
First boot: resize to max size of SD card. Enable camera support
Login: pi/raspberry

Change super pass to "pi"
sudo passwd
# introduce new password

Enable camera in RPi configuration

Enable camera in condif
raspi-config
Enable camera ..

Check camera configuration

Login as super and take a snapshot: http://www.raspberrypi.org/documentation/usage/camera/raspicam/raspistill.md
DATE=$(date +"%Y-%m-%d_%H%M")
raspistill -vf -hf -o /home/pi/camera/$DATE.jpg

Install mono
apt-get update
apt-get install mono-runtime
apt-get install mono-complete

Check if is Mono was installed correctly
Create a file named "HelloWorld.cs" and write the following code inside

#####
using System;

public class HelloWorld
{
public static void Main()
{
Console.WriteLine("Hello World!");
}
}
#####
Compile and run it
gmcs HelloWorld.cs
mono HelloWorld.exe