I am guessing, of course, but I think that the film speed setting on the camera is set at too high a number. If you are unsure as to how to set this, you can find the manual here. Of course you should make sure you have a good battery.
Further, set the camera to the speed using the number on the film box. If you are using the camera properly and it is working correctly you will get lovely photos. You can adjust the film speed after you've learned the basics. Finding a friend who is familiar with manual cameras is a good idea. They are easy to use once the basics are understood. In any case, make sure you go through the manual carefully. Cameras from that era are simple to understand and the Yashica manuals were good for teaching beginners.
Good luck and let us know how things work out.