2003 Toyota Camry emissions trouble code P0456

I have a 2003 toyota camry with about 60,000 miles. The check engine light has started going off. My code reader shows code P0456: EVAP emission control system leak (very small). I spoke with toyota service techs and verified that I ALWAYS make sure to click the gas cap at least once after filling. I see there is a fuel filler neck corrosion issue after researching the internet. I checked and do have the corrosion. I used steel wool to remove some and lubed the ring. How do I replace the fuel filler neck myself? I plan to start by replacing the filler cap and see if that takes care of the code.