Well, when you post, you can choose whether you want to 100% powerup, or whether you want 50/50 pay out. Ill come back to that.
After you have posted, people can vote for you, and the potential pay-out will rise.
This pay'out is not entirely for you, some goes to the voters as an incentive for voting.
If you chose 100% powerup, youre payout will be in the form of steempower, making you a more powerfull user. You cannot immediately cash this out.
If you chose 50/50, half of the payout is steempower, half is in steemdollard. These czn be transferred, or converted to steem. The conversion on this website assumes that 1steem dollar = 1 $. Actualky steem dollars trade over 2$, so it is a better plan to sell them for steem on the internal market, rather than convert them (youll get more steem)