I have a .Net user control that creates nodes dynamically and pops them under a selected parent node. The code is below.

I want to assign values to the three properties of my created node, but can't seem to hit on the right syntax. Can anyone help? I'm writing in C#

//create node           
string strDocumentName = DateTime.Now.ToString("yyyy_MM_dd_HH_mm_ss_ffffff");           

DocumentType dt = DocumentType.GetByAlias("Comment");
            
//author uses a dummy user called CommentWriter
User author = User.GetUser(2);           

Document doc = Document.MakeNew(strDocumentName, dt, author, _intParentId);

//add properties??

doc.Publish(author);
umbraco.library.UpdateDocumentCache(doc.Id);