Welcome!
The knowledges help item should be unlocked during the tutorial. In case it was not, then this is probably a bug we need to solve. Please feel free to send us any additional details regarding this issue.
Here is a list of the powers used to decide upon the Expert achievement:
- lightning bolt
- fire ball
- resurrection
- curing a weak disease
- curing a serious disease
- curing a permanent disease
- healing a weak injury
- healing a serious injury
- healing a permanent injury
- growth spurt
- rejuvenation
- fertilization
- fire extinction
- gender swap, male to female
- gender swap, female to male
- earthquake
Every one power in the list above must be cast at least once for the Expert achievement to be unlocked. This can be tricky indeed, especially regarding the multiple heal/cure/swap variations.
Hope this helps.