Problem in creating table at runtime in c#.. Plz Help Dear ones... URGENT

As Aleksandar indicated, it is not clear whether you need to create tables or create rows in tables. I will assume you need to create rows in tables, but that does not make sense since you have only one field in your form so the new rows will have just one field.

First I suggest you open the connection only once for the form, so add the following member to the form class:

SqlConnection con;

Then in the form's Load event do something such as:

try { con = new SqlConnection("Data Source=localhost;Initial Catalog=Northwind;User Id=sa;Password=sa");
con.Open();
}
catch (Exception ex)
{
MessageBox.Show("Connection error: " + ex.Message);
Close();
}

And in the form's Closed event:

 con.Close();

Then in the button click you can do something such as:

try
{
String CommandText = String.Format("Insert Into {0}({1}) Values (@FieldData)", textBox1.Text, textBox2.Text);
SqlCommand InsertCommand = new SqlCommand(CommandText, con);
InsertCommand.Parameters.Add(new SqlParameter("@FieldData", textBox3.Text));
InsertCommand.ExecuteNonQuery();
}
catch (Exception ex)
{
MessageBox.Show("Insertion error: " + ex.Message);
}

But note that as I said, that will create a new row with just one field, and I doubt that is what you need.

Can you clarify what you need to do?