How to using sha256 encrypt password on login page in C#

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C#

i want to try sha256 encrypt password store in Database and making login page with encrypted password

protected void submit_Click(object sender, EventArgs e)
   {
       if (Session["CAPTCHA"] != null && Session["CAPTCHA"].ToString().Equals(txtcaptcha.Text) && Validation.ValUsername(username.Text) && Validation.ValPassword(password.Text))
       {
           SqlConnection cnn = new SqlConnection();
           cnn.ConnectionString = ConfigurationManager.ConnectionStrings["MCC"].ConnectionString;

           SqlCommand cmd = new SqlCommand("select  * from [EmployeeList] where userid = @name", cnn);
           cnn.Open();
           cmd.Parameters.Add("@name", SqlDbType.VarChar).Value = username.Text;
           SqlDataReader dr = cmd.ExecuteReader();

           if (dr.HasRows)
           {
               dr.Read();

               string rnostr = Convert.ToString(Session["rnumb"]) + dr["password"].ToString();
               MD5 md5Hash = MD5.Create();
               string strHash = GetMd5Hash(md5Hash, rnostr);

               if (strHash.ToLower().Trim() == password.Text.ToLower().Trim())
               {
                   Session["id"] = dr["ID"].ToString();
                   Session["role"] = dr["role"].ToString();
                   Session["level"] = dr["Level"].ToString();
                   Session["designation"] = dr["designation"].ToString();
                   Session["name"] = dr["Name"].ToString();
                   Session["mobno"] = dr["MobileNo"].ToString();
                   Session["email"] = dr["Email"].ToString();
                   Session["ip"] = Request.UserHostAddress;

                   Random rd = new Random();
                   HttpCookie ck = new HttpCookie("mcc");
                   ck.HttpOnly = true;

                   Session["ck"] = GetMD5.getMD(rd.Next().ToString());
                   ck["rnd"] = Session["ck"].ToString();
                   Response.Cookies.Add(ck);

                   Database.LogData("Login", username.Text + " " + Session["name"].ToString(), Request.UserHostAddress, Session["id"].ToString(), "");

                   if (Session["role"].ToString() == "admin")
                   {
                       Response.Redirect("~/Auth/adm/Map.aspx", false);
                   }
                   else if (Session["role"].ToString() == "user")
                   {
                       Response.Redirect("~/Auth/usr/OfficerInbox.aspx", false);
                   }
                   else if (Session["role"].ToString() == "entry")
                   {
                       Response.Redirect("~/Auth/rpt/EnterGrievanceUser.aspx", false);
                   }
                   else if (Session["role"].ToString() == "complaint_entry")
                   {
                       Response.Redirect("~/Auth/rpt/EnterComplaint.aspx", false);
                   }
                   else if (Session["role"].ToString() == "GPU")
                   {
                       Response.Redirect("~/Auth/adm/GPUBinCheck.aspx", false);
                   }
                   else if (Session["role"].ToString() == "SanitaryAdmin")
                   {
                       Response.Redirect("~/Auth/adm/BinMaster.aspx", false);
                   }
                   else if (Session["role"].ToString() == "Report")
                   {
                       Response.Redirect("~/Auth/adm/LocWiseReport.aspx", false);
                   }

                   else if (Session["role"].ToString() == "Nodal")
                   {
                       Response.Redirect("~/Auth/usr/ComplMark.aspx", false);
                   }
               }
               else
               {
                   Database.LogData("LoginFailure", username.Text, Request.UserHostAddress,"", "");
                   MessageBox("Incorrect User Name or Password");
               }
           }
           else
           {
               Database.LogData("LoginFailure", username.Text, Request.UserHostAddress, "", "");
               MessageBox("Incorrect User Name or Password");
           }
           dr.Dispose();
           cnn.Close();
       }
       else
       {
           Database.LogData("LoginFailure", username.Text, Request.UserHostAddress, "", "");
           MessageBox("Incorrect verification string or username or password");
       }
       Random rd1 = new Random();
       MD5 md5Hash1 = MD5.Create();
       string strHash1 = GetMd5Hash(md5Hash1, rd1.Next().ToString());
       Session["rnumb"] = strHash1;
       hfrandam.Value = Session["rnumb"].ToString();
       //submit.Attributes.Add("onClick", "return EncryptPassword1('" + Session["rnumb"].ToString() + "');");
   }

function EncryptPassword1() {
try {
var x = document.getElementById('').value;

if (document.getElementById('').value == '') {
alert('Enter username');
document.getElementById('').value = ''
document.getElementById('').focus();
return false;
}

if (document.getElementById('').value == '') {
alert('Enter password');
document.getElementById('').value = ''
document.getElementById('').focus();
return false;
}

if (document.getElementById('').value != "") {
var md5encypt = hex_md5(document.getElementById('').value);
var passstr = x + (md5encypt);
document.getElementById('').value = hex_md5(passstr);
}
}
catch (err) {
alert(err.message);
}
}

What I have tried:

i want to try sha256 encrypt password store in Database and making login page with encrypted password