The track command is used to add tracked time in the past. Perhaps you forgot to record time, or are just filling in old entries. For example:

$ timew track :yesterday 'Training Course'
$ timew track 9am - 11am 'Staff Meeting'

Note that the track command expects a closed interval (start and end time), when recording. If a closed interval is not provided, the 'track' command behaves the same as the 'start' command.