You want to apply a pea sized dot of thermal paste onto the CPU very gently
We have a video below that shows you how to go about doing this.
You don't want to put too little because it can overheat or too much because it can spill into the motherboard and cause a short.
If you're not comfortable doing this please call us at 305-971-1000. Extension 1 for sales, 2 for support.
It's recommend to reapply thermal paste once every 6 months to prevent overheating.
How To Apply Thermal Paste