Hello there, steem dollar is meant to be a token that peg with USD, so each steem dollar is supposed to be $1 each. You need to convert steem dollar into steem before converting to steem power. Steem power is like the equity of steemit, the more steem power, the more influential you are in steemit.
RE: Can anyone help explain what are the purpose of Steem,Steem power and Steem dollar