Adjust tax return

I’m just getting around to sorting my taxes.
I have filed a form 11 for 2011 last year and have done a prelim for 2012.
I have a sterling account in NI going open for 13 months.
I have to declare the interest on this account and I haven’t informed revenue about it yet.
What form would I now use or what is the actual procedure for letting revenue know and paying the dirt ?

Did you file your Form 11 through ROS?
Just have a look and see if there is an option to amend the 2011 return. Agents can do that for their clients, just not sure if the individual taxpayer can.
You would then pay any extra liability online.

No my accountant filed my form 11 for 2011.
I now want to do my own accounts.
Without doing 2012 accounts now I wonder what is the best way of getting it sorted.