Hi James :)
When you talk about the integers modulo 3 (or modulo any number) you're basically talking about the remainder left over if you divide by 3. so, there are three elements in the set, 0, 1, and 2. so 2 + 2 = 4 (normally), but if you divide 4 by 3, the remainder is 1, so 2 + 2 = 1...