Setting the aperture on a 35-70mm lens?

I never used a 35mm film slr camera before. On the Nikon FM10's kit lens the aperture is 3.5-4.8 I think. If I set the aperture ring to 3.5 i can use it at 35mm but at longer focal lengths how does that work? It's not a constant aperture lens. I know on a DSLR it will automically choose the next f stop usable on the focal length I think that's how it is.

Added (1). Mmm so If I set the aperture to let say f4 at 70mm which is not possible will there be a light indicating I have to put a smaller aperture?

What you're reading is that at 35mm the f'/stop is 3.5. Zoomed in, because less light can get in, it's
f/4.8 Those are the widest the lens will go. The smallest will be much higher, f/18 perhaps.

You have figured it all out.

As you learn to use the light meter with some ease, you will find that every time you press the shutter release, you will produce nearly perfect exposures.

Here is the user manual if you don't happen to have yours. Even if you do, you can use the "Find" feature in Adobe Acrobat to search its contents

http://www.butkus.org/chinon/nikon/nikon_fm-10/nikon_fm10.htm