Adding block to content area programatically

gistfile1.cs

GetBlocks(aboutPage.TopLeftContentBox)
    .Select(block => new ContentAreaItem()
    {
      ContentLink = ((IContent)block).ContentLink
    })
    .ToList()
    .ForEach(cai => aboutPage.AdditionalContent.Items.Add(cai));

_contentRepository.Save(aboutPage, SaveAction.Publish);