This is just like adding a gadget to a blog with a designer or layout template, ie:
Go to the Layouttab (Design > Page Elements, if you’re using pre-Sept-2011-Blogger)
Click Add A Gadget.
Choose your gadget, and configure it if necessary. (NB Blogger appear to be converting all the existing gadget setup screens to the new-interface-look-and-feel, so don’t be surprised if the buttons etc inside the gadget parameter windows look different)
Preview to check it’s OK.
Click Save Arrangement.
It’s not perfect yet. The layout editor window looks somewhat strange, in post-Sept-2011-Blogger anyway: More importantly, Blogger’s announcement says
Gadgets supported in Dynamic Views currently include: Blog Archive, Followers, Labels, Profile, Subscribe (a new gadget – automatically present if either Follow By Email or Subscription installed), and Link List.
Dynamic View – Time Slide
So no HTML, no AdSense, no Blogroll(except you can make your own with the Link List), Statistics, Slideshows, Polls, etc … yet. To make matters worse, there’s nothing to tell you what gadgets you cannot add: you put them in, but they’re just not there once you save and look at the blog. You Can Add Adsense by Editing Post in HTML. But some of them may become available, if Blogger can figure out how to place with within the type of space they’re using for gadgets on dynamic views, where we don’t really have a sidebar. And until then, the following section from my original post still applies.