During my application, I show database table inside a datagridview. Now I wish to modify and alter some records and save this changes on database. How do i do that?

TableAdapters are just one way of doing the work.

 objDataAdapter.SelectCommand = new SqlCommand();
        objDataAdapter.SelectCommand.Connection = objConnection;
        objDataAdapter.SelectCommand.CommandText = "select code,name,family,fatherName,age from bimar";
        objDataAdapter.SelectCommand.CommandType = CommandType.Text;
        objConnection.Open();
        objDataAdapter.Fill(objDataSet, "bimar");
        objConnection.Close();
        dataGridView1.AutoGenerateColumns = true;
        dataGridView1.DataSource = objDataSet;
        dataGridView1.DataMember = "bimar";

i personally use this code to exhibit my table on DataGridView , i wish to after doing a bit of focus on DatagridView the information will get placed to db

Here's an example with BindingSource:

      string query = "SELECT * FROM dbo.bimar";
      da = new SqlDataAdapter(query, connectionString);
      SqlCommandBuilder cBuilder = new SqlCommandBuilder(da);
      dt = new DataTable();

      da.Fill(dt);

      BindingSource bSource = new BindingSource();
      bSource.DataSource = dt;

      dataGridView1.DataSource = bSource;

whenever you improve your data in dataGridView1 , update it:

 private void button1_Click(object sender, EventArgs e)
    {
        da.Update(dt);
    }