Well there used to be a link at the top of the page with a piece of paper icon labeled documentation.
The nice people at OTN obvioulsy realized that this was a massive waste of resources that could potentially lead to a stampede of people reading the manuals instead of asking the same questions over and over again on the forums, thereby reducing traffic to about three posts a year instead of the several billions or shedfull of lahks we enjoy now.
So now you have to try one of these
I also start with http://docs.oracle.com because it's easier to memorize.
I have to say the search function on Oracle document site is really not very good. A lot of time you have to know where to search or which book to start with.