What you are actually saying is that you want more of your muscle to show. There is one of two ways to do that. You can build muscle which means excess calories and fat or shed fat which means calorie deficit and lose some muscle. Naturally, there unfortunately is no way around that. You can gain strength but that will mostly be neurological adaptation.

So to answer your question, you must ask which one is more important. At 66, I'd say lose fat. In which case, I'd want to get the fat burning portion done first. So I'd do the cardio or HIIT training and then hit the weights.

You can combine weights into an HIIT workout that would help with your strength - which is also very important as we get older. This is probably too advanced for a beginner, but I do a medley of strength implements for my cardio work - prowler, yoke bar, farmers handles.

Seriously you may look into a group class like Body Pump. It ain't no joke if you put the work into it.

Bottom line, though, do something. Do anything. Find something you enjoy. Going for a walk is even a good place to start. Just don't stagnate