If you want to manipulate the market you throw down a huge amount of Bitcoins on the Ask side so you literally flood the market with coins thus making an "ask wall". This will (in theory) drive the prices down so that you can then buy-in artificially cheaper and reward yourself on the way back up when people follow.
Aha...
Why don't you also mention the reverse possibility of people throwing down a huge amount of bitcoins on the bid side to drive the prices up so they can sell at a high price ?
Actually why do all your post seem to be trying to rise the price of bitcoins ? And masking that as a "newbie helper" ! A bull in sheep's clothing !
P.S.
All you people thanking Flip for the advice bear (no pun intended) in mind he has his personal interests in manipulating other people's opinion, just like 99% other people here. Belief makes prices, not reason, and who controls belief controls prices.