SPFolder documents = web.GetFolder(url);
FileStream fileStream = File.OpenRead(documentPath);
SPFile file = documents.Files.Add(various override methods);

SPDocumentLibrary docLibrary = documents.DocumentLibrary;
var documentTemplateUrl = docLibrary.ContentTypes[1].DocumentTemplateUrl;
byte[] stream = web.GetFile(documentTemplateUrl).OpenBinary();
SPFile fileTest = documents.Files.Add();