Assuming you are writing your own Documetnum client you would do something like this using DFC:
IDfClient dfClient = new DfClientX().getLocalClient();
IDfDocbaseMap dfDocbaseMap = dfClient.getDocbaseMap();
for (int i = 0; i < dfDocbaseMap.getDocbaseCount(); i++) {
String docbaseName = dfDocbaseMap.getDocbaseName(i);
String docbaseDescription = dfDocbaseMap.getDocbaseDescription(i);
//... do your thing for each pair docbaseName, docbaseDescription; eg.
System.out.println(docbaseName + " | " + docbaseDescription);
}
I suggest you dig a bit through Documentum API (DFC) like here