wwwXigniteComServices.XigniteGlobalCurrenciesSoap testCls = new wwwXigniteComServices.XigniteGlobalCurrenciesSoap();

wwwXigniteComServices.Header h = new wwwXigniteComServices.Header();

h.Username='****';
h.Password='****';
h.Tracer='****';
testCls.Header = h

testCls.GetRealTimeRate('EURUSD');

wwwXigniteComServices.XigniteGlobalCurrenciesSoap testCls = new wwwXigniteComServices.XigniteGlobalCurrenciesSoap();

wwwXigniteComServices.Header h = new wwwXigniteComServices.Header();
h.Username='daniel.ballinger@example.com';
h.Password='notMyRealPassword';
h.Tracer='51ED22B1IAMWEASELF1CFF9650B4'; //Found value in API Tokens on xignite website
testCls.Header = h;

wwwXigniteComServices.Rate eurUsdRate = testCls.GetRealTimeRate('EURUSD');
System.debug(eurUsdRate);