I try to use the Umbraco 8 documentation but some things do not work for me. I took the following lines from the Umbraco documentation but the Content object does not exist:

@{
    var site = Model.Content.Site();
    var doThis = Umbraco.TypedContent(123);
}

I also tried to access the content directly from database but again I had the same result:

@{
    var dontDoThis = ApplicationContext.Services.ContentService.GetById(123);
}

Do I have to add a reference or a using in my view?

Thanks in advance for your help.