You will need a tube of Arctic Silver 5.
You will need a bottle of ArctiClean Thermal Surface Purifier.
You will need a few Coffee Filters. You can buy these from Walmart in the Coffee isle.
Remove the plastic cover from the base of the Heat Sink.
Apply a few drops of ArctiClean solution to the base of the Heat Sink.
Wipe the surface clean using a Coffee Filter.
Apply a few drops of ArctiClean solution to the surface of the CPU.
Wipe the surface clean using a separate Coffee Filter.
Squeeze out a little bit of Thermal Paste from the tube to make a short vertical line as shown below.
The picture below shows the ideal amount of Thermal Paste that you should apply.