Go to /system/admin.pma, then click the 'Configuration' tab. This will allow you to edit all the serverside configuration files (everything in the /config/ folder ending in *.config).
Next select httphostmap.config from the dropdown list and the file contents will be displayed.
Edit as required. You can map host names and/or URIs (paths), eg:
...so in your case:
Click the 'Save Configuration' button.
Finally, the change won't be immediate. Click the 'Console' tab and enter the command 'tell http hostmap reload'. Done. Test by entering the URL in your browser and your application should be shown.