You have to install the software to the PC via either download and run a typical installation on the PC or via the disk that came with your device.
The PC version is included in most install disks for the Palm Desktop but it is not part of the normal installation. You usually have to install it via "add on" from the Palm Desktop installation disk.
Therefore, insert your Palm Install disk and it should come up with a "add" additional software or browse additional software and then look for the DTG program group usually nested under "Personal Productivitiy" heading. Although it could be a stand alone category depending upon your device.
If you continue to have issues - post back what type of device - cuz not all of them come with DTG as standard.