WorkOrder TS Backup files are compressed files which can contain your configuration files, uploaded files and a backup of your database.

First you should look at the log file, backup_log-2009-03-16_1556.txt in this example.
The file contains information from the different programs used to generate your backup, here is an example of a file with no errors.

Creating Working Sub-Directory
Coping uploads directory
1 File(s) copied

Coping configuration files
2 File(s) copied

Creating database backup....
Database dump complete, please check for an error message between this line and the line:
Creating database backup

Creating zip file of backup
7-Zip (A) 4.65 Copyright (c) 1999-2009 Igor Pavlov 2009-02-03
Scanning
Creating archive C:\Backups\workorder_ts\WorkOrder_TS-Backup-2009-03-16_1556.zip
Compressing WorkOrder_TS-Backup-2009-03-16_1556\config-guest.inc.php
Compressing WorkOrder_TS-Backup-2009-03-16_1556\config-user.inc.php
Compressing WorkOrder_TS-Backup-2009-03-16_1556\uploads\index.html
Compressing WorkOrder_TS-Backup-2009-03-16_1556\WorkOrderTS-Database_dump-2009-03-16_1556.sql

Everything is Ok
Backup should be complete now, removing files

And here is a file with errors after the line "Creating database backup"

Creating Working Sub-Directory
Coping uploads directory
1 File(s) copied

Coping configuration files
2 File(s) copied

Creating database backup....
mysqldump: Got error: 2003: Can't connect to MySQL server on 'localhost' (10061) when trying to connect
Database dump complete, please check for an error message between this line and the line:
Creating database backup

Creating zip file of backup

7-Zip (A) 4.65 Copyright (c) 1999-2009 Igor Pavlov 2009-02-03
Scanning
Creating archive C:\Backups\workorder_ts\WorkOrder_TS-Backup-2009-03-28_1550.zip
Compressing WorkOrder_TS-Backup-2009-03-28_1550\config-guest.inc.php
Compressing WorkOrder_TS-Backup-2009-03-28_1550\config-user.inc.php
Compressing WorkOrder_TS-Backup-2009-03-28_1550\uploads\index.html
Compressing WorkOrder_TS-Backup-2009-03-28_1550\WorkOrderTS-Database_dump-2009-03-28_1550.sql

Everything is Ok

Backup should be complete now, removing files

If the log file shows no errors it is time to extract the backup.
Once extracted you should see the files you requested the backup script to compress for you.
In this example I have the uploads directory, the configuration files and the database dump inside the archive.

Now open the database backup file, WorkOrderTS-Database_dump-2009-03-28_1550.sql, in this example and scroll all the way down to the last line which should read "-- Dump completed on 2009-03-28 14:50:02". The important part here is that the last line reads "-- Dump completed" the date should be correct but the time might be off by a few hours but this depends on your server configuration.

If all this checks out you know your backup is valid and complete. You should check your backup files every once in a while to ensure that nothing on your server has changed which prevents the backup from executing