UPdating database from dataGrid

[Swami]

I have a DataGrid that loads data from an Access database...I want the user
to be able to edit the values, add new rows, or delete values in the data
grid, and have the changes sent back to the database...I tried using the
DataAdapter.update() method, but I am gettign errors...here's my code:

private void BudgetDialog_Load(object sender, System.EventArgs e)
{
dataGridBudget.DataSource = GetBudget().Tables["Budget"];
}

private void buttonEdit_Click(object sender, System.EventArgs e)
{
dataGridBudget.ReadOnly = false;
buttonEdit.Enabled = false;
}
private void buttonSave_Click(object sender, System.EventArgs e)
{
DataTable dt = (DataTable) dataGridBudget.DataSource;
DataSet ds = dt.DataSet;
commandBuilder.DataAdapter.Update(ds, "Budget");
}

public DataSet GetBudget()
{
string queryString = "SELECT Category, Amount FROM Budget WHERE Month = 8";
connection = new OleDbConnection(connectionString);
dataAdapter = new OleDbDataAdapter();
dataAdapter.SelectCommand = new OleDbCommand(queryString, connection);
commandBuilder = new OleDbCommandBuilder(dataAdapter);

try
{
connection.Open();
DataSet ds = new DataSet();
commandBuilder.DataAdapter.Fill(ds, "Budget");

return ds;
}
catch (Exception ex)
{
return null;
}