Sega Saturn emulation is a mess. For years, the only way to accomplish it was through a butchered (and thoroughly illegal) repackaging of Sega's own commercial emulation software, which was intended for used with a scant handful of games (and the limited scope showed). In the decade or so since, only one emulator, SSF, has managed to surpass this trainwreck, and most of its documentation is in Japanese. You can download SSF from this page (click the link with the date, at the top).
If you haven't been scared off yet, you'll be pleased to learn that the emulator runs out of the gate almost as simply as any other. Download the app, unzip the package, open the program, and the first thing you'll need to do is give the emulator a CD drive to read from. This option appears on the first tab of the Options menu (which, thankfully, is entirely in English) under 'CD Drive'. Because SSF is a rather literal-minded emulator, you don't open a ROM or anything similarly straightforward; instead, choose Reset from the Hardware menu after mock-inserting (that is, pointing it toward) a CD.
Regrettably, SSF doesn't support ISOs natively. Normally, you would use a disc image to fake a CD drive using software like Daemon Tools. But because SSF doesn't use the same method of detecting CD drives that practically every other piece of software on your computer employs, some virtual drives may not show up in SSF. In our last assessment, the emulator correctly detected Daemon Tools drives, but not those created by PowerISO.
Burning the actual game CDs won't make things any easier. The process requires decade-old freeware tools that may no longer exist on the Internet, and it's so complex that you may decide that you don't really want to try Panzer Dragoon Saga after all. If you have original discs, more power to you; the emulator will read them without a fuss.
Fortunately-ish, the author has been kind enough to let you configure more of the technical aspects of the emulation than any human being apart from himself and three guys who left Sega a decade ago could possibly understand. To avoid having to think too much about this, you'll want to use the 'EZ Setting' tab on the options menu (to the far right), which provides a handful of configuration presets. If games are running too slowly (which they seem to do quite at random, independent of your system specs), select low compatibility for a speedup; if they're crashing, choose high compatibility (avoid 'very high', as it's prohibitively slow).