Code:
//check if childs name and month have been selected
if (cmbChildName.Text == "")
{
    MessageBox.Show("Please select a childs name");
}
else if (cmbMonth.Text == "")
{
    MessageBox.Show("Please select a month");
}
else
{
    //show each of the controls
    foreach (Control ctrl in this.Controls)
    {
        ctrl.Visible = true;
    }
    
    //disable combos
    cmbMonth.Enabled = false;
    cmbChildName.Enabled = false;
}