How Does Steemit currency or rewards works and how to use it. Help Needed.......

Hi Friends,

As recently i have completed my first week on Steemit and i have received rewards/Steem power/Steem Dollars, but am not sure how does it works in terms of income. So i would be glade if I am being assisted on this Steem rewards on how to make use of it.
Also how much does the this Steem rewards value in real world when its being transferred.

It would be happy to hear some good and easy understanding guidelines on this so that it will be very helpful for me in future and also it will helpful for other newbie on Steemit.

Thanks in Advance Guys.