Readings
Required reading for the week.
This is required reading; you can't go wrong with the Web Style Guide.
This is a lengthy article, but well worth reading all the way through. You may not be able to apply much of it now, but this is essential stuff to know if you want to be a web professional.
Create your diagramming approach using specific advice presented here.
WordPress
Joomla
Drupal
A different perspective on useability, site design, and how user's really see and interact with sites.