using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace MyApp
{
    public partial class TextBoxPalceHolder : Form
    {
        public TextBoxPalceHolder()
        {
            InitializeComponent();
        }
        private void TextBoxPalceHolder_Load(object sender, EventArgs e)
        {
            this.ActiveControl = label1;
            textBox1.GotFocus += new EventHandler(this.TextGotFocus);
            textBox1.LostFocus += new EventHandler(this.TextLostFocus);
        }
        public void TextGotFocus(object sender , EventArgs e)
        {
            TextBox tb = (TextBox)sender;
            if (tb.Text == "Your Text ..........")
            {
                tb.Text = "";
                tb.ForeColor = Color.Black;
            }
        }
        public void TextLostFocus(object sender , EventArgs e)
        {
            TextBox tb = (TextBox)sender;
            if(tb.Text=="")
            {
                tb.Text = "Your Text ..........";
                tb.ForeColor = Color.LightGray;
            }
        }
    }
}

<script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=false&libraries=places&language=vi-VN"></script>

<script>

var autocomplete = new google.maps.places.Autocomplete($("input[id*=DiaChi]")[0], {});

google.maps.event.addListener(autocomplete, 'place_changed', function() {

var place = autocomplete.getPlace();

});

</script>