To put on the thermal compound (arctic silver 5) you want to remove the heatsink, and scrap off the thermal compound that was used orginally by the manufacture. You can do this with a credit card, or something similar! If worse comes to worse you can run a hair-dryer over it for just a moment to heat it up, which may make it easier to remove the compound, just a moment though. After all of the compound is removed. DON'T go crazy with the compound, just a small dot. Smaller than a pea. You want to spread this it either using your finger (protected by a rubber glove) or a credit card, or something along these lines. You want a PAPER thin layer. Litterally... using more will come back and bite you right in the a$$. GL!