SOAP API Passing credentails to XML envelop

I’m working on an integration with Clarity( Broadcom) - using a soap execute to import data from a Query.
In the soap envelope – I need to pass Username and Passoword for authentication . How can I pass credentials securely from account ( basic OAUTH)? It is not taking parameters like account.Username and account.passoword ?

<soapenv:Envelope xmlns:obj="http://www.niku.com/xog" xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">
      <soapenv:Header>
        <Auth>
        <Username>account.username</Username>
        <Password>account.password</Password>
        </Auth>
      </soapenv:Header>
      <soapenv:Body>
           <Query xmlns="http://www.niku.com/xog/Query">
        <Code>test_delete</Code>
            </Query>
      </soapenv:Body>
      </soapenv:Envelope>