Enable example extensions
From OpenKM Documentation
In order enable OpenKM extension go to Administration tab and click on Database query button. Then select JDBC and register the extensions in your DBMS.
ToolBarButtonExample
INSERT INTO OKM_EXTENSION (EXT_UUID,EXT_NAME) VALUES('9f84b330-d096-11df-bd3b-0800200c9a66','Toolbar button example');
TabWorkspaceExample
INSERT INTO OKM_EXTENSION (EXT_UUID,EXT_NAME) VALUES('44f94470-d097-11df-bd3b-0800200c9a66','Tab workspace example');
TabFolderExample
INSERT INTO OKM_EXTENSION (EXT_UUID,EXT_NAME) VALUES('d95e01a0-d097-11df-bd3b-0800200c9a66','Tab folder example');
HelloWorld
INSERT INTO OKM_EXTENSION (EXT_UUID,EXT_NAME) VALUES('d9dab640-d098-11df-bd3b-0800200c9a66','Hello world example');
After that, you also need to enable the proper extensions in Administration > Profiles.