Many items under the Help menu did nothing (Help Topics, Contact Support Team, Submit Feedback) when I first started.
I found File / Settings / IDE Settings / Web Browsers. Multiple installed browsers were checked; at the bottom under Default Browser was "System default" (Firefox on my system) -- but no browser would open. When I changed that to "First listed" (which happens to be Chrome) then "Help Topics" opened Internet Explorer (how odd -- Firefox is the default browser and Chrome is listed first). Changing it back to "System default" again causes Help Topics to be a no-op.
Apparently the only fully-configured browser, by default, was IE. Only by fiddling around (specifying the Chrome executable path as the "Custom path", then changing to "first listed" [chrome]) could I get anything other than IE to open. (Firefox has never opened -- I guess it won't until I tell IDEA its path. Isn't it in a standard place on everyone's system, like IE?)
Meanwhile, I couldn't do anything run-like until a JDK was configured. (Why, when no JDK is configured, doesn't it open a dialog to configure one rather than displaying a "no JDK" message with no clue what to do?) The Wiki shows steps for a different version. Only when I found File / Other Settings / Default Project Structure could I configure an IDEA-wide JDK. It's not even possible to do it in Project Settings. Sheesh.