learn ruby on rails

i’m doing my homework i try build a simple web app based on rails, but i face difficulty to visualize my app with UML. i don’t know how to make a UML based on Rails, is that rails have “special treatment” to visualize with UML, or what? i try to find an article or maybe a sample of UML that match with my difficulty, but i still can’t find that. i hope someone can help me to show me “the light” :D, i will appreciate that..

i’ve started learn RoR, and i feel it’s fun… but a now i still get stack on “layout”ing thing. im confuse how to create, manage,... a layout on the “big” website, shortly… when a user have logged on the ‘block’ fav. site will appear and other block (guest’s) will dissappear. maybe this is really simple for someone out there..but i must find the answer… try try and try