Symbols will appear in the drop down box after you have used them in something like a chart. To do this please add a chart and click the magnifying glass search icon, search for the symbol and open a chart. The symbol should now be available in the drop down menu.
You can refer to page 27 of our users' guide. Once you click on the Define button from the Configure > Instruments menu, you will be able to fill in the fields. It's pretty straight forward. As an example, you can always right click on any of your present charts and select Edit Instrument to see what the filled in fields look like for a presently defined instrument.