Whole Code

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using SKYPE4COMLib;

namespace TutorialOne
{
    public partial class Form1 : Form
    {
        private Skype MySkype = new Skype();
        public Form1()
        {
            InitializeComponent();

        }

        void MySkype_MessageStatus(ChatMessage pMessage, TChatMessageStatus Status)
        {
            if (pMessage.Body[0].ToString() == "@") // Check if it is a command, @ can be anything that you want.
            {
                string Command = pMessage.Body.Substring(1, pMessage.Body.Length - 1); // Basicaly remove @ from it.
                if (pMessage.Sender.Handle != MySkype.CurrentUserHandle) // Check if the sender is not yourself.
                    MySkype.SendMessage(pMessage.Sender.Handle, ProcessCommand(Command)); // Send the message back.
                else
                    MessageBox.Show("Message not sent.");
            }
        }

        private string ProcessCommand(string cmd)
        {
            switch (cmd)
            {
                case "help":
                    return "The commands are: blablabla...";
                case "LOL":
                    return "(chuckle)";
                default:
                    return "This is not a command.\nSend '@help' for help.";
            }
        }

        private void ConnectButton_Click(object sender, EventArgs e)
        {
            MySkype.Attach(5, false);
            MessageBox.Show("Hello " + MySkype.CurrentUserHandle);
            MySkype.MessageStatus += MySkype_MessageStatus;
        }

        private void SendMessageButton_Click(object sender, EventArgs e)
        {
            MySkype.SendMessage("guibbsbr", "I am using your source :)");
            // You could also use a TextBox to get both variables,
            // just make sure to check if them are not empty/null.
        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }
    }
}