This is easy to do. If you have a SQL helper class use that or you can use the SqlCommand object and the SqlDataReader along with the SqlConnection.
Something similar to:
dr = cmd.ExecutReader();
if (dr.HasRows)
{
dr.Read();
textbox1.Text = dr["FirstField"].ToString();
textbox2.Text = dr["SecondField"].ToString();
}
so on and so forth.