Share Options sold in 2007 - Letter from Revenue

Hi, I received a letter from Revenue stating I sold share options in 2007 for 2400 euro and the relevant tax is now due. I didn't pay any tax when I exercised these share options (it was due 30 days after exercise date...). Am I liable to penalties now? I will pay the tax due but I worried about penalties, etc.
The letter stated I need to complete a RTSO1 form and also I need to attached a Form 11 for 2007. Can I do this myself or do I need an Accountant.
How much tax do I need to pay and do I have to pay penalties?

Unfortunately interest will be due on the unpaid tax. A surcharge may also be due for non submission of the tax return. The form RTSO1 and Form 11 are available on Revenue's website and you can complete these yourself fairly easily. If you want some help calculating the payment due and completing the forms let know. I will need some more info re the share options e.g excercise date, excercise price, date of sale of shares if different to exercise date etc. PM me the info if you need any help.

Thanks Breninio, I PM'd you with more details.
The letter didn't state that interest is due or surcharges so would I be billed for these after I pay the required tax on the share options net gain?
Form 11 looks complicated enough to fill out - do I just fill out the share options section?