Connection-Authentication from CRM Online Plugin to SharePoint online

I am writing a plugin in Dynamics CRM on Opportunity Update and want to send Opportunity data to SharePoint Online List as an Item.

I was using the following details to connect to SharePoint on Premises that worked fine, but now when I connect to SharePoint Online it generated "Access Denied" etc Security Error.

string _siteUrl = "mxxxxxx11.sharepoint.com";
string _userName = "xxxxxxx365@XXXXXX.onmicrosoft.com";
string _password = "pXXXXXXX23";
string _domain = "mydemo11@onmicrosoft.com";

com.sharepoint.domain.Lists listService = new com.sharepoint.domain.Lists();
listService.Url = _siteUrl;
listService.Credentials = new System.Net.NetworkCredential(_userName, _password,_domain);

System.Xml.XmlNode ndListView = listService.GetListAndView("Account", "");
string strListID = ndListView.ChildNodes[0].Attributes["Name"].Value;
string strViewID = ndListView.ChildNodes[1].Attributes["Name"].Value;

The above code worked for on Premises SharePoint Server but not for SharePoint Online,

Please guide me how to connect to a SharePoint Online from CRM online Plugin.