.It's actually that simple. This will require the latest version of any package published to npm. This works from the embedded version of Tonic, too.
Requiring specific versions
If you want to require something other than the most recent version, just append @ to the end of the package name. For example, require("firstname.lastname@example.org").
Searching for packages
You can also search for packages by clicking the search button in the top right corner of the window:
This will bring up a search interface, complete with links to the homepage of each package and the README if one is available.
Just click the "require" button (or double click a package from the list) and a require statement will be inserted into your notebook.