Validate multiple textbox or other entries

Given is the validation code for my form.

private void button1_Click(object sender, EventArgs e)
 {if (txtName.Text == string.Empty)
            {MessageBox.Show("Enter the name");txtName.Focus();
            }if(dateTimePicker1.Value.Date > DateTime.Now)
            {MessageBox.Show("Invalid date");

            }
            if (!rbtMale.Checked && !rbtFemale.Checked)
            {MessageBox.Show("Choose the gender");
            }if (txtAddress.Text == "")
            {MessageBox.Show("Enter the address");txtAddress.Focus();
            }if (txtContact.Text == "")
            {MessageBox.Show("Enter the contact info");
            }if (cmbCountry.Text == "")
            {MessageBox.Show("CHoose your country");
            }
}

What i want to do is just show one message box saying form is not filled. And to highlight the empty fields.