The most up to date help, with links to other music related topics, is on RecordingBlogs.com.
The time line is a thin horizontal panel at the top of Orinj that shows the current time. The time is in the format mm:ss:ms (minutes, seconds, milliseconds), but how much is shown depends on the current zoom. The further you zoom in, the more detail you will see. The time line shown above is common to all Orinj views, except for the loop building view.
The time line in the loop building view is the thin panel in the picture above. The buttons of this time line light up during playback to show the current position of the playback.