There are 12 marks (out of 70...) for testing and test plans - so they're important! It's rows f and g of the markscheme you need to consider: row f is in the prep work; row g is in the exam.
1. Plan first:
a) You need (second row of f):
- a plan which shows how you will test each individual element of the spreadsheet. This means each time data is entered, a button pressed, an option chosen or a spinner or tick box or something clicked.
- this plan needs to be in a sensible order
- it needs to say what you're going to do, what data (precisely) you're going to test the spreadsheet with, and what exactly the expected output is (bear in mind, doing something on one worksheet might have an impact on several worksheets)
- a plan for the whole system - i.e. taking a series of clients through the spreadsheet from start to finish as if they were doing it for real
- this needs to include the expected output as well
- there must be sets of test data (second mark requires this)
For row g all you do is actually follow the test plan through and provide evidence of doing so. It's important in this bit to show whether or not the actual outcome is what you expected it to be.
This means for both parts of the test plan - the individual testing elements and the whole system testing
Here's a hint - this will need a bunch of screenshots and might take a while. Numbering your tests will make this a load easier.
You'll also want to look at Testing, Testing 124 which I blogged last year (it's about databases but it'll kinda work) as well as Normal, Extreme and Erroneous which I'll blog in a minute.