How to implement correctly ReadXML() method?

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XmlSerializer

deserialization

Hi guys! I have to ask you help for XML serialization.

I have to deserialize this XML document (a piece of electronic invoice):

<ElectronicInvoice>
  <Header>
    <Transmission>
      <Id>
        <IdCountry>IT</IdCountry>
        <VatNumber>12345689</VatNumber>
      </Id>
      <Code>123456</Code>
      <TransmissionFormat>ABC</TransmissionFormat>
      <Contacts>
        <Phone>05512345</Phone>
        <Email>foo@mail.com</Email>
      </Contacts>
    </Transmission>
  </Header>
</ElectronicInvoice>

I try to deserialize with XMLSerializer, so each class in ElectronicInvoice has to implement IXMLSerializer interface.
How can I implement the ReadXML() method?

Sorry for my english. Thank you in advance.