Cannot get C# to work with solidworks at all... Please Help

Recently I just started using C# to develop something to work with Solidworks.

Someone please help me to get started...

Below just the code to change a dimension in a opened document(I added two COM reference just as they instructed here):

=========================================

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;

namespace ccccc

{

    public partial class Form1 : Form

    {

        public Form1()

        {

            InitializeComponent();

        }

        private void button1_Click(object sender, EventArgs e)

        {

            SldWorks.SldWorks swApp;

            swApp = new SldWorks.SldWorks();

            SldWorks.ModelDoc2 Part;

            Part = swApp.ActivateDoc;   //Cannot convert Object

            Part.Parameter("D1@Sketch1").Systemvalue = 0.1;

            //swApp.ExitApp();

            //swApp = null;  

        }

    }

}

======================================

However, Visual Studio complain about the code in red colour?!!

Please help how to write that part please... I just need to assign opened document to it, but it refuse to work!

SolidworksApi macros