using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.Office.Tools.Ribbon;
using Microsoft.Office.Tools.Excel;
using Microsoft.Office.Interop.Excel;

namespace ExcelAddIn2
{
    public partial class Ribbon1
    {

        private void Ribbon1_Load(object sender, RibbonUIEventArgs e)
        {

        }

        private void GetRageValues()
        {

            Range range = Globals.ThisAddIn.Application.get_Range("A1", "A3");

            //to be replaced with database insert
            System.Windows.Forms.MessageBox.Show("You Selected" + range.Address);
        }

        private void button1_Click_1(object sender, RibbonControlEventArgs e)
        {
            GetRageValues();

        }

    }
}

Microsoft.Office.Interop.Excel.Range SelectedRange = Globals.ThisAddIn.Application.Selection;