I don't recall any guide actually being created for this. So here goes.
How to make HP pots
Go the the sundries, buy the scroll of favours. You need a MINIMUM of 10 scrolls. 1 scroll = 1 hp pot.
I'm making 100 pots here
Go to the potions NPC, buy these vials. You need a MINIMUM of 10 vials. 1 vial = 1 hp pot.
Quick SS of my inventory to show what you should have before you make pots (scrolls & vials)
Go to Grand Celebrant, highlight her (left click), then enable her menu (right click on her), choose the following option
You will get the following box, click I confirm
Here is the box, it shows you how many pots you have made, click the confirmation box to confirm and receive your pots.