hole
The 'cover' they might be talking about could be the starter. Some enigines with the same block and transmission case, were sold as hand crank models or electric start. The ones with just hand crank will have a cover where the starter goes, but no starter. If you take your starter out, use WD-40 or something else to clean around the opening and there will be a small stamped line. The markings on the flywheel are evident, and should be clean if you have an engine with the flywheel in oil. Or it could be kind of dirty if there is a dry clutch in there. In that case you may need to clean the flywheel a little to locate the marks.
Flywheels are the most unforgiving part of a motor. Once you get them spinning just a little they don't want to stop and they love to nip off parts of your fingers. If you can at all help it do not stick your fingers in the hole and try to turn the flywheel. Crank it from somewhere else.
I don't know what your engine looks like or anything about it. I am just guessing about the starter being the cover, it could be somewhere else.