Hi. In the margin on the left of the screen <--- there is a link called Books, which is a good place to start. Some of them are kindly provided for free 🙂 but obviously you can buy them too.

Also you might enjoy Brent Ozar's Accidental DBA 6 Month Training Plan (below-also free). You get an email a week and they're very interesting. The whole blog is good actually- have a read!

http://www.brentozar.com/archive/2013/07/announcing-our-free-accidental-dba-6-month-training-plan/