<soapenv:Header>
      <wsse:Security soapenv:mustUnderstand="1">
         <wsse:UsernameToken>
            <wsse:Username>username</wsse:Username>
            <wsse:Password Type="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-username-token-profile-1.0#PasswordText">password</wsse:Password>
         </wsse:UsernameToken>
      </wsse:Security>
   </soapenv:Header>

private String passwordField;

public string Password
{
    get { return this.passwordField; }
    set { this.passwordField = value; }
}

public UsernameToken(string username, string password)
{
    this.Username = username;
    this.Password = password;
}

[XmlAttribute("Password", Namespace = "http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-username-token-profile-1.0#PasswordText")]
public string Password
{
  get { return this.passwordField; }
  set { this.passwordField = value; }
}