Creating a Form with some formula

Hi, I am completely new at this forum. So, If I have made any mistake sorry for that.

My Requirements::

I want to build a Form using Adobe Live-Cycle Designer. The Form will be like a Order Form and the Problem is that I want to use some formula or you can say Javascripts for some specific fields in that form.

1. Fields: There will be 9 column. Calculation parts will be associated with 5 columns and with a extra field named "Grand Total". So, I will discuss only about those 5 columns and a extra field named "Grand Total".

Field Name::

i. Price Per A4 Paper- In dozens.

ii. Price Per A3 Paper (sold in 10 dozens only.)

iii. Order Type (This field will be a Dropdown menu with 2 options 1. A3 & 2. A4)

iv. Quantity

v. Subtotal.

vi. Grand Total

Conditions:

1. If A4 is Chosen then the "Subtotal" cell will calculate "Quantity" by the price that is listed on the "Price Per A4 Paper" field.

2. If A3 is Chosen then the "Subtotal" cell will calculate "Quantity" by the price that is listed on the "Price Per A3 Paper" field. The quantity will be multiplied by 10.

3. "Grand Total" Will Calculate all subtotals boxed for Quantity and Price.

4. "Price Per A4 Paper- In dozens." & "Price Per A3 Paper (sold in 10 dozens only.)" fields can be editable in future only by the administrator.

Problems::

1. I have very poor idea about JavaScripts. Though I have applied them successfully in the webpages but I have no idea how use them in Live Cycle.

2. You can think that You will be showing road to a 90% blind person. :P

Waiting for experts comments and suggestions.

Thanks,
Bangla Lovers.