If they didn't come with the machine, order the 'Single Wall Filter Set BSWF100' for the Breville 800ES from your local Breville repair/spare parts shop. Use the 2 cup single wall filter with around 16-18 grams of finely ground fresh roasted coffee tamped down with the correct size (51mm) tamper to around 30lbs pressure (use bathroom scales to check).
The aim is to extract around 60mls in 30 seconds for the 16-18grams through the 2 cup single wall filter. Once you have achieved this extraction rate, play around with the 'brew temperature' by temperature surfing. This should be able to be done by delaying the time you brew from when the brew light indicates it is up to temperature. It will slowly cool until the thermostat kicks back in and reheats giving the spread of a few degrees to play with. Mine is a different machine but when using the same grind, I find if the temperature is too hot the taste is bitter and if too cold the taste for me is sourish. I'm still experimenting and learning but I hope this may be of some help. On this forum the minimum recommended grinders to achieve a consistent fine grind seem to be the Sunbeam EM0480 or the Breville Smart Grinder BCG800. I bought the Sunbeam for $136 a short while back but in some respects with I had paid the extra for the Breville. The Sunbeam seems to retain fine grinds inside the machine and even after tapping on the bench there are still more than desired left inside. This can't help the taste of the brew. Wasting beans to push out old grinds between brews seems such a waste!