How to fill a combobox using database

Public Class Connectionclass

    Private Sub btnins_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnins.Click
        cboname.SelectedItem = txtn.Text
    End Sub


End Class

private void CategoryParent()
{
    using (SqlConnection Con = GetConnection())
    {
        SqlDataAdapter da = new SqlDataAdapter("Select Category.Category from Category", Con);
        DataTable dt = new DataTable();
        da.Fill(dt);
        CBParent.DataSource = dt;
        CBParent.DisplayMember = "Category";
    }
}