Oh god not another one- please don't remove that top screw. BAD, BAD JUJU. If you do, and it will be a long bolt, you will have successfully dis-assembled your starting clutch lever. Your moped will not start or run if you do this.
On level ground, use a funnel, or the top off of a gear oil bottle to pour fluid into the transmission hole on the side. You can use either type F or type III. Then, run it around for a little while, and top it off again, just to make sure.
If you run low on fluid, the engine will bog down heavily, and possibly die when you stop.