I think you are loosening the inspection cover on the front. It looks just like the rear timing mark inspection cover. Remove it and under that is a 17mm nut on the end of the crankshaft. Turn this nut in a clockwise (tightening) direction. That will rotate the engine.
Make sure that you are at TDC (top dead center) on the compression stroke and the TDC mark on the flywheel is on the mark before you start adjusting the valves. TDC will occur twice on every revolution of the engine, but the compression stroke only happens once. You can also tell by the tappets all being loose at this point. You should be able to move them slightly, not much, but just a bit. Another way is to watch the action of the intake valves. They will open, then close on the compression stroke. As the valves close, watch for the TDC mark at the inspection hole. Do the left side first, (on your left as you are sitting on the bike), then turn the engine to where the right cylinder is at TDC for the right side. Cam chain adjustment is also done with the left cylinder at TDC.