1. Add HTML Page from C3 Add New Item
2. Put html inside
3. Drag and drop the html (e.g. HTMLPage1.html) file into your Resources tab in the project:
4. Use code below 
        private void button1_Click_1(object sender, EventArgs e)
        {
            string html = Properties.Resources.HTMLPage1;
            string tmpFileName = Path.ChangeExtension(Path.GetTempFileName(), ".html");
            using (StreamWriter sw = File.CreateText(tmpFileName))
            {             
                sw.Write(html);
                sw.Flush();
            }
            if (File.Exists(tmpFileName))
                Process.Start(tmpFileName);
        }