Have you not done any of it in your first three years of secondary school?
Anyway, I did graphics for GCSE (AQA) and in our school we either had to design a clock or a board game (I chose the game). This was for the coursework and most of the lessons were focussed on that because you kind of learn the theory stuff whilst doing the coursework. We had to produce a big portfolio thing with research on board games and whatever theme you chose, rough design ideas, progressing onto final drawings of what the game will be like and how you're going to make it. You then make it and record what you did and take photo's etc. My folder was really quite big, there's actually a lot to keep record of and design (In my case it was the game and the box it came in). We used graphics computer programs for the graphics on the box and on the games/ clocks, but you will need a bit of practical skills as well to actually make your product.
On the theory side, we looked at mass production, the effects of different colours, company logos (designing a logo was a big part of the exam - we were given a theme a few weeks before to research images and do a few vague designs, then given what we actually had to design in the exam), and of course, technical drawing. There is obviously more but I did the GCSE a whole year ago now :P:
Though of course this could all be very different to your school and exam board.