Just read the instructions carefully and watch some videos on how to apply the thermal compound efficiently across the CPU surface. That is, if you don't know how to do it.
I usually do the "apply and spread". Clean the surface of the CPU (if its dirty with human grease or dirt) and be careful about not touching it directly with your hands at any time. Then, apply one "drop" (it's not liquid; watch a video for this) of thermal compound in the middle of the CPU and then spread it with something like a ruler over the surface leaving a very thin cover and no visible area without thermal compound.