At some point you should learn about pattern code and rewrite rules. And AFAIK the information is super limited. The is some info here:
http://www.refactory.com/the-rewritetool. There are also nice in-Pharo help chapters ���Refactoring Framework > RB Refactoring Engine��� which explain matchers and so on. Don���t rush with this, first figure out how the other things work, but maybe someone can refer to more literature.
After you learn that, maybe you can write a few blogposts about ���starting with pattern syntax and rewrite rules���.
Cheers.