The log files are created in the Saved folder of your Project folder. This link will show where to find the files on your machine: A new, community-hosted Unreal Engine Wiki - Announcements - Epic Developer Community Forums
The second box under the Editor Session Logs heading is the logs we would need. Make sure you completely exit the editor after obtaining the first file before attempting to get the second. You may also need to add “.txt” to the file names for them to upload to AnswerHub properly.