Send Email from Gmail in asp.net 2.0

protected void btnSendEmail_Click(object sender, EventArgs e)
{
//Create Mail Message Object with content that you want to send with mail.
System.Net.Mail.MailMessage MyMailMessage = new System.Net.Mail.MailMessage("dotnetguts@gmail.com","myfriend@yahoo.com",
"This is the mail subject", "Just wanted to say Hello");

MyMailMessage.IsBodyHtml = false;

//Proper Authentication Details need to be passed when sending email from gmail
System.Net.NetworkCredential mailAuthentication = new
System.Net.NetworkCredential("dotnetguts@gmail.com", "myPassword");

//Smtp Mail server of Gmail is "smpt.gmail.com" and it uses port no. 587
//For different server like yahoo this details changes and you can
//get it from respective server.
System.Net.Mail.SmtpClient mailClient = new System.Net.Mail.SmtpClient("smtp.gmail.com",587);

//Enable SSL
mailClient.EnableSsl = true;

mailClient.UseDefaultCredentials = false;

mailClient.Credentials = mailAuthentication;

mailClient.Send(MyMailMessage);
}

Writing XML file from dataset and Reading XML file into dataset

Writing:

OleDbConnection con = new OleDbConnection("connection string");
OleDbDataAdapter da = new OleDbDataAdapter("select * from tbl_emp", con);
DataSet ds = new DataSet();
da.Fill(ds, "emp");
ds.WriteXml("d:xmlformat.xml", XmlWriteMode.IgnoreSchema);
//this will create an xml file in "D" drive.

Reading:

DataSet ds = new DataSet();
ds.ReadXml(@"d:\xmlformat.xml");
GridView1.DataSource = ds;
GridView1.DataBind();

Retrieve Single Value from DataTable/Dataset

DATATABLE:

Object o = dataTable.Rows[0]["ColumnNameOrIndex"];

DATASET:

Object o = dataSet.Tables[“TableNameOrIndex”].Rows[0]["ColumnNameOrIndex"];

Working with Abstract classes, Sealed Classes, and Interfaces in C#

http://aspalliance.com/1213_Working_with_Abstract_classes_Sealed_Classes_and_Interfaces_in_C.all