Yep, block feeding is just feeding only from one side for a certain number of feeds/period of time. So if LO is feeding every 2-3hr, start off doing two feeds off the left, then the next two feeds off the right, etc. If LO is feeding frequently (due to gas discomfort, hiccups, etc. this is sometimes the case), make it a set period of time, so feed off the left for 4hr, then the right for 4hr (ie, every feed between 7am and 11am from the left and so on).
The idea is that the engorged breast tells the body to stop producing milk, there's plenty here already. It really helped down-regulate my supply to something approaching manageable.