How do I add Segments of Time in Numbers '09?

Question

Aloha:
I am trying to wean myself off of Microsoft... so I'm trying to set up a TV Show Rundown sheet in Numbers.  I can do it easily in Excel but can't figure it out in Numbers.  Help....
After a Description Column, I have two columns displaying Time.  The Left Column shows the length of the specific segment and the Right Column shows when it begins within the total Elapsed Time.  For example:
show open id     0:00:15    0:00:00
Opening VO      0:00:45     0:00:15
Title Package    0:00:20     0:01:00
On Camera 1     0:01:30    0:01:20
So the 1st element is 15 seconds long, and it starts at 0:00:00 on the clock
The 2nd element is 45 seconds long, and it starts at 0:00:15 on the clock
The 3rd element is 20 seconds long, and it starts at 0:01:00... one minute in
Th 4th element is 90 seconds long, and it starts at 0:01:20...
And so on.  In Excel, I would set up the two columns with the right display but enter the data as clock time.  So the 1st element is 15 seconds long, but if you double click on the cell, you would see it as 12:00:15 AM but when you released the cell it read as 0:00:15.  In Excel, I could just set up a simple formula where it added those 2 cells in the row above it.  It returned a running time, and I could just keep entering segment times.  I could time out elements for a 30 second spot or a 60 minute show.  I also use it to time the songs in any given set of music my band plays.  A very simple way to add up discreet moments of time passing.
If I'm reading Numbers correctly... which I may not be doing... it doesn't seem to want to add up two time entries.  But then I read Duration is perfect for adding Time.  But beyond formating the cells as Duration, I'm just not seeing the next step.  Plus if I enter in any number like "2", the display says 2h 0m 0s. 
Can someone show me the right direction to go?  Thanks in advance for any tips...

Answer 1

"I used to enter in a lot of Time Code into Word.  I would use the numeric keyboard and some third party software that changed the key strokes.  In Word, I would change "Opt ." in the numeric keyboard to ":".  And "Shift ."  would type as ";".  I could very quickly enter in numbers like14:23:18;00 just on the numeric keyboard."
You might find what you need in the article Automatically Substituting Text in Chapter 8, Working with Text, of the Numbers '09 User Guide (excerpt below). You can download the guide (and the iWork Formulas and Functions User Guide) via the Help menu in Numbers.
To replace one or more characters with one or more different characters, select
“Symbol and text substitution.” Then use the rows in the table to define and activate
specific substitutions. For example, when you type (c), you can have Numbers
automatically convert it to © by putting a checkmark in the On column. To add a row
to the table to define your own substitution, click the Add button. To remove a
selected item, click the Delete (–) button.
After you specify substitution settings, they’ll apply to any text you change or add in
any Numbers spreadsheet.
Regards,
Barry