Moving data from form to collapsible table

Hi guys, I just wanted to get some advice on how I could do this. I need to create a form, and the form will have the inputs

Category
Name
Group
Date
Cost

I come from an Object Orientated background so I would consider that when the data is entered and submit is pushed, an Object is created. So this part is easy enough, but then I need to take this data and pre-populate a calendar type table.

The table will be a collapsible type table, and the simplest form the initial table will look like

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Advertising	£1453	£1453	£1453	£1453	£1453	£1453	£1453	£1453	£1453	£1453	£1453	£1453
Electricity	£80	£80	£80	£140	£80	£140	£140	£80	£80	£80	£80	£80
Wages	£22,343	£22,343	£27,343	£22,343	£22,343	£34,343	£22,343	£29,343	£22,343	£22,343	£34,343	£22,343
Marketing	£600	£600	£600	£600	£1200	£1200	£1200	£600	£600	£600	£600	£600

The titles down the left, Advertising, Electricity, Wages, Marketing come from the form input Category. These are the main categories which will selected from a drop down menu. The money comes from all objects under that category for that month, added together. When you click on a category, it should expand and display the Name, Group, Date and individual cost of each object. So if you create 12 objects under the category Advertising, when you click on it in the table, it will display 12 rows of data.

So doing the form is simple. I am really looking for advice on how to map this into the table and how to make everything collapsible. Any advice is appreciated, I am not to sure how to start on this part.

Thanks

Nick

p.s. sorry for the bad title, I have changed it to make it more appropriate.