The Second Year part of the History course is called "Studies of Change". You'll learn how Ireland, Europe and the wider world changed from the Middle Ages and its feudal ways and into the modern world that you live in now. The end of the Second Year course leaves off just about where Third Year picks up - the beginning of the 20th Century.
Of course, in Second Year there will be more things to learn than there was in First Year (same as it is with every other subject), but every topic you study this year is divided into three sections: the causes of the event, the course (story) of the event, and the consequences (results) of the event. Learn the topics this way and Second Year will be easy.
Second Year might seem less interesting at first than First Year, but many of the topics give you the background you need to understand topics you'll study next year. For example, the story of the Plantations is important for understanding the story of Northern Ireland in Third Year. Halfway through the year you'll start looking at the most dramatic kinds of change: revolutions.