That's the first thing to check. The flash sync speed is the fastest shutter speed that can sync with a flash, so you can use a slower one too. Some cameras sync faster, but most manual cameras are 1/60 so try that one for starters. Flash exposure is determined by the aperture (and also film speed), and f5.6 is pretty normal for camera mounted flashes when you're trying to light something say 6-10' from the camera. Try f5.6 at 1/60 and it should work assuming that the flash has some sort of an auto mode on it. You can tell this (what flash is it?) by looking at the back of it - some of them have a distance range (or ranges shown in different colors) based on the aperture and film speed you're using, and a switch on it somewhere with the corresponding color (blue range, red range, etc).