I in case you haven't read it already, read the comment above/below that I replied to. BTW, you earn steem power when you chose 100% steempower on the content you post. However, when someone upvotes you or when you upvote other people, when you redeem your rewards (author/curating) you will be reward some steem too. Also, when you get reward steem dollars or steem, you have the option of transfer/converting to steem power. I believe, that in the early stages it is more important to convert/transfer to as much steem power as you can, because then people will be motived to follow you and upvote your post more when they see that your upvotes contribute to them...