tabs

please help me i m new in symbian development .i m making a application with two tabs ,
two views and two containers. i wrote resources in rss . implemented offer key event funtion
but i still i am not able to switch between tabs..plzz tell me where to declare n define navi decorator
and i wrote this code in container.cpp
TKeyResponse CMultiViewsContainer1::OfferKeyEventL(const TKeyEvent& aKeyEvent, TEventCode aType)
{
if (aType != EEventKey)
{
return EKeyWasNotConsumed;
}

CAknTabGroup* iTabGroup = (CAknTabGroup*) iNaviDecorator->DecoratedControl();
if ( iTabGroup == NULL )
{
return EKeyWasNotConsumed;
}

TInt active = iTabGroup->ActivateLocalViewL();
TInt count = iTabGroup->TabCount();

switch ( aKeyEvent.iCode )
{
case EKeyLeftArrow:
if ( active > 0 )
{
active--;
iTabGroup->ActivateLocalViewL(TUid::Uid(EMultiViewsView2Id));
}
break;
case EKeyRightArrow:
if( (active + 1) < count )
{
active++;
iTabGroup->ActivateLocalViewL(TUid::Uid(EMultiViewsView2Id));
}
break;
default:
return EKeyWasNotConsumed;
break;
}
but the error is coming that unidentified identifier i navi decorator and ative local viewL
plzzz tell me where to define n how