if you want to compile C# source code in ubuntu, then you should install mono.

sudo apt-get install mono

then you have to install this package also

jacobian@jacobian-laptop:~$ sudo apt-get install mono-gmcs

then open mono in your applications tab and open a file that has a C# source code in it. For this time I made a helloworld program based on C#.

this is the code

using System;
using System.Collections.Generic;
//using System.Linq;
using System.Text;

namespace HalloWorld
{
public class Hallo_World
{
public static string BacaInput(string msg)
{
Console.BackgroundColor = ConsoleColor.Green;
Console.ForegroundColor = ConsoleColor.Blue;
Console.Write(msg);
Console.BackgroundColor = ConsoleColor.White;
Console.ForegroundColor = ConsoleColor.Red;
return System.Console.ReadLine();
}

public static void TulisKonsole(string msg)
{
Console.BackgroundColor = ConsoleColor.Black;
Console.ForegroundColor = ConsoleColor.Yellow;
System.Console.WriteLine(msg);
}

static void Main(string[] args)
{
Console.BackgroundColor = ConsoleColor.DarkMagenta;
Console.ForegroundColor = ConsoleColor.Yellow;
Console.WriteLine("iNILAh VisuaL C ShaRp");
Console.WriteLine("=====================");
Console.WriteLine("");
string nama = BacaInput("sILAkan Masukkan Nama Anda: ");
TulisKonsole("Selamat DAtang ke Dunia C Sharp, " + nama);
Console.ReadLine();
}
}
}

and then I open this file with mono and run it. Then it will give this output.

iNILAh VisuaL C ShaRp
=====================

sILAkan Masukkan Nama Anda: Selamat DAtang ke Dunia C Sharp,

C# is a good language for programming, I think you should learn it.

C#