1. You'll first need to install the Diploma Test Generator on a computer. There is a user guide available online to assist with this process: http://www.wimba.com/support/webhelp/v6_6/DiplomaWinUser/Diploma_User_Guide.htm
2. You'll want to reference Moodle's user documentation about importing questions for information on the file type to export from the Vistas test generator: http://docs.moodle.org/20/en/Import_questions
3. After you have the test generator installed and you've referenced the Moodle documentation (see step 2), you'll want to use the "Export" feature in the test generator to export test bank files. See the Exporting section in the In-Depth Help folder in the Diploma online user guide (see step 1).