OK, I understand bidding on the search network using keywords. (Doing it now.) I know all the options for content placement bidding, but I'm kinda of fuzzy on how everything relates. Let's say I want my ads to only appear on one website that's related to my niche. Do I need to enter any keywords related to my niche, then edit the manage placement choices? Adwords seems to be asking me to enter keywords before I choose my location. If I don't have to enter any keywords, then how does Google decide that my webpage is relevant to a website of my choosing? By how much I bid? Does that mean I'll be competing with the highest bid keyword on each page? (There's normally tons of keywords about anything and everything on a typical page.) Are all pages on the website cost the same when I bid via the content network? If I bid too low, will I only end up on the "crappy" pages, or not at all?