Once you find your dream home (or something close to it), it's time to get in there and start the bidding. Your agent, if you go that route, can help you decide what to offer -- it'll most likely be below what the sellers are asking, but going too low is risky. You could seem like you're not a serious buyer.
You'll need to pay "earnest money" so the sellers know you're not fooling them. You could lose this money (typically several thousand dollars) if the sellers accept your offer and you then break the contract after a pre-set deadline.