SyndicationItem item = new SyndicationItem("My Item", "This is some content", new Uri("http://SomeServer/MyItem"), "Item ID", DateTime.Now);
item.Authors.Add(new SyndicationPerson("[email protected]", "Jesper Aaberg", "http://contoso/jesper"));
item.Categories.Add(new SyndicationCategory("Category One"));
item.Contributors.Add(new SyndicationPerson("[email protected]", "Lene Aaling", "http://contoso/lene"));
item.Copyright = new TextSyndicationContent("Copyright 2007");
item.Links.Add(new SyndicationLink(new Uri("http://OtherServer/Item"), "alternate", "Alternate Link", "text/html", 1000));
item.PublishDate = new DateTime(2007, 2, 23);
item.Summary = new TextSyndicationContent("this is a summary for my item");
XmlQualifiedName xqName = new XmlQualifiedName("itemAttrib", "http://FeedServer/tags");
item.AttributeExtensions.Add(xqName, "ItemAttribValue");

SyndicationFeed feed = new SyndicationFeed();
Collection<SyndicationItem> items = new Collection<SyndicationItem>();
items.Add(item);
feed.Items = items;