// Initializes a new abstract list instance.
AbstractListAdv abstractListAdv = new AbstractListAdv(null);
abstractListAdv.AbstractListId = 1;

// Defines new ListLevel instance.
ListLevelAdv listLevel = new ListLevelAdv(abstractListAdv);
listLevel.ParagraphFormat.LeftIndent = 24d;
listLevel.FollowCharacter = FollowCharacterType.Tab;
listLevel.ListLevelPattern = ListLevelPattern.Bullet;
listLevel.ParagraphFormat.AfterSpacing = 8d;
listLevel.NumberFormat = "\uf0b7";
listLevel.CharacterFormat.FontFamily = new FontFamily("Symbol");

// Adds list level to abstract list.
abstractListAdv.Levels.Add(listLevel);

// Adds abstract list to the document.
textbox.Document.AbstractLists.Add(abstractListAdv);

// Creates a new list instance.
ListAdv listAdv = new ListAdv(null);
listAdv.ListId = 1;
listAdv.AbstractListId = 1;

// Adds list to the document.
textbox.Document.Lists.Add(listAdv);

// Add content
ParagraphAdv paragraph = new ParagraphAdv();
SpanAdv span = new SpanAdv();
span.Text = "Item 1";
paragraph.Inlines.Add(span);
paragraph.ParagraphFormat.ListFormat.ListId = 1;
paragraph.ParagraphFormat.ListFormat.ListLevelNumber = 0;
textbox.Document.Sections[0].Blocks.Add(paragraph);

ParagraphAdv paragraph2 = new ParagraphAdv();
SpanAdv span2 = new SpanAdv();
span2.Text = "Item 2";
paragraph2.Inlines.Add(span2);
paragraph2.ParagraphFormat.ListFormat.ListId = 1;
paragraph2.ParagraphFormat.ListFormat.ListLevelNumber = 0;
textbox.Document.Sections[0].Blocks.Add(paragraph2);