This article (first Google result) explains the rules succinctly.
And my video here explains how to use Minnowbooster to do it.
Steem is confusing, because it is its own economy with rules that are different from other cryptocurrencies. It is more like a social media co-op than a cryptocurrency, imo.
Haha, oh no, I did it to myself: http://lmgtfy.com/?q=Steem+delegating
Haha, yes, but you also gave me the opportunity to link my YouTube video, so all is forgiven. :-)