The interest is added to your income. You will need to file a tax return by Oct 31st Tax - see
www.revenue.ie for details. Income tax and/or PRSI will be due at your marginal rate.
Depending on a number of factors - for example, the country where the trading account is held, your tax status, ... - foreign tax may or may not be due, may or may not be deducted by the account holder, the income may or may not be reported to the Irish tax authorities and may or may not be allowable against any irish tax due.
Sorry to be so imprecise but you question leaves out so many important details that a more definite answer is impossible.