I did a quick google search and found this link for the FG http://www.mir.com.my/rb/photography...0/fg/index.htm
I have an old Nikon FM from about the same time frame. Although it does not have any automatic features the rest of the build is similar. I'm assuming that you are used to using point and shoot digital cameras. With these types of camera when you look through the viewfinder, you are not looking through the lens.
This may be obvious but, did you remove the lens cap?With any SLR (single lens reflex) camera be it film or digital, when you look through the viewfinder the mirror in the camera brings in the image through the lens.
As for needing batteries to use it, you will need them for the built in light meter, but should not to look through it.
To learn to use it, check online for manual for the camera. You can also look online or check out a book or two at the local library on basic photography to tell you all about ISO (or ASA filmspeed) exposure settings, etc.
I hope this helps you and good luck, you will have fun learning it.