Topping is just simply cutting the top node off of a plant so that i will grow two dominant colas. You can then top those and get four colas.
FIM'ing or FIM stands for FUCK I MISSED. Its when you prun the top but you prune in the middle of the ttiny bit of new growth at the top of the plant. This way all of the veins of the new growth will become there own branches, so you can FIM once and get say 8 or so main colas, usually you get 4 or 5 though.
Search for FIM in google pictures and you will see where to cut. Lamp