You cannot mine Steem at all!

(But soon you can mine new accounts!)

There is no proof-of-work as with Bitcoin and many other coins. All transactions are near instant and don't need any special computational power. They also have zero transaction fees because nobody needs to be rewarded for any mathematical problems to be solved. Hence, the only way to create Steem is by receiving an upvote on a post or comment or by receiving curation rewards or beneficiary rewards from other people's post (which is currently not feature on Steemit but does exist on Steem).

All other ways to receive Steem are somehow related to your Steem Power via delegations or vote selling or stuff like that. Check out my investor guide linked above for more info about what you can do with Steem power to earn Steem.