Reference guide:
https://wiki.openmrs.org/display/docs/HTML+Form+Entry+Module+HTML+Reference
Form bank:
https://wiki.openmrs.org/display/RES/Form+Bank
Flowsheet: HtmlFormFlowsheet Module
Flowsheet (video):
https://www.youtube.com/watch?v=DfnjSRCo-ZY
Training materials:
https://wiki.openmrs.org/display/RES/Htmlform+Implementers+Training
JavaScript examples:
https://wiki.openmrs.org/display/docs/HTML+Form+Entry+JavaScript+Reference
...