XML : Write WCF element at same level

I'm new to WCF and .net world.

We have a WCF Service. In this we need to have the region wise contact's email Ids under the region name like:

  <ContactRegion> <RegionName>Canada</RegionName> <Contact>abc@xyz.com</Contact> <Contact>abc1@xyz.com</Contact> <Contact>abc3@xyz.com</Contact> </ContactRegion>    

Can you please Suggest me how we can get this kind of structure and the Model Classes hierarchy structure to be used to get this?

Note: Our Classes are Serialized we are not generating custom XML.

Thanks For Your Support In Advance!