I was trying to create file but unable to get option of create or log to txt file.
You can write content to a file in many different ways, you need to specify what you are trying to save ?
Also, logs should be saved in OpenFlow using the Activities under OpenFlowDB, and not in a file on the disk, but if that is what you prefer you can use this from “Invoke Code” activity.
System.IO.File.AppendAllText("c:\temp\file.txt", "My Test" + Environment.NewLine)