The stack script of the HyperBBS Home stack is where most of the methods and functions are for the BBS. If you're planning to modify the BBS in any major way, you'd best print out and study that script in some detail.
The methods contained in the Home stack script include ones for handling card text display, user text input, user filling of fields, user pushing of buttons, creating new users, logging in and out new and old users, and a variety of additional, miscellaneous items.
See the Generic Operation section for more details on "normal" operation.