I'd like to create hyperlinks in my blog to Wikipedia.  For instance, if I'm writing about Greta Garbo, I'd like to make the words "Greta Garbo" a hyperlink to her entry in Wikipedia. 
  I don't see any way to do this in the formatting controls.  Am I missing something?

Highlight the text, click the "chain" icon.

Thanks for your help!  I should have seen that.  I feel incredibly stupid now, like I just walked out of the latest Paris Hilton film  lol

Well, at the risk of being stupid, I must say that I have already tried that.  Maybe I am missing a step or?
When the text is highlighted and the link (chain) icon is clicked, what looks like a dialogue box opens, but nothing can be entered in either the small url space (which has an address of an HP location in it) or in the larger white area below that.  An attempt to paste brings a "bing" from the computer and an attempt to click and type in either space results in nothing appearing.
So what's up?

Sounds strange. Whenever HubPages is being strange, refresh or control+refresh.

Nine times out of 10, that will fix it.

Jenny