Module Automatic Instantiation
You need to type the first letters of the module name, then press Ctrl+Space three (3) times. You can recognize module instances by their icon, it looks like a chip with ports ready to be glued in.
You can customize what gets generated from menu Window > Preferences > DVT > SystemVerilog > Editor > Content Assist in the Auto-instantiation section.
Autoinstance of library modules
For performance reasons, only the modules which are actually used in the design are compiled from -y libdirs and -v libfiles. However, DVT can help you instantiate any of the available library modules:
When picking a library module auto-instance proposal, the selected module is first compiled and then the instance is computed and inserted in code.
Note
Because only the libdirs and libfiles which are actually used in the design are scanned at compile time, the list of auto-instantiation proposals may contain an entry to discover modules in unused libraries.