You can add new symbols to Condes' symbol palette.  When Condes is active, but no Event file is open, a menu item, Symbols, will appear in the main menu.  This menu item has three sub items, New symbol, Open symbol, and Delete symbol.  These menu items can be used to manipulate the symbols.

New symbols can be designed using a drawing program, and imported to Condes via a Windows Metafile Format (.WMF/.EMF) file, or via the clipboard.

WARNING:  Changing the symbol database can have unwanted effects.  Do not change the symbol database unless you are absolutely certain that this is what you want to do.