You can add web pages using SPLimitedWebPartManagerand your web page definition URL. In this example, you need to start:
XmlTextReader reader = new XmlTextReader(new StringReader(web.GetFileAsString(<Url to your .webpart file here>)));
SPLimitedWebPartManager wpm = web.GetLimitedWebPartManager(<URL to your page>, Syste.Web.UI.WebControls.WebParts.PersonalizationScope.Shared);
WebPart wp = (WebPart) wpm.ImportWebPart(reader, out errMsg);
wp.Title = "My Title for this webpart";
wpm.AddWebPart(wp, <Name of WebpartZone here, e.g. "Header">, <Zone Index here>);
wpm.SaveChanges(wp);
WebPart . SPLimitedWebPartManager.ImportWebPart SPLimitedWebPartManager.AddWebPart, WebPart .