Nikon D5000 pictures are all black when using manual telephoto lens. How do I adjust?

Please, I don't need to hear "Buy an auto lens.". Lol I need to know why my shots are all coming out completely black unless I take a shot of a light. I can see my subject in live view and viewfinder. But in settings, it displays f-- and flashes a question mark. When I press the question mark button, it says "Subject is too dark. Can't adjust exposure." I have my dial set to M. My autofocus lenses work perfectly. How can I set it to show f-8 to f-22 instead of f--? What am I doing wrong? Thanks!

Added (1). It's just a Rokinon 500mm f8 to f32 telephoto lens. It has a 2x teleconverter. I bought it from Cameda Cameras on ebay. They said it was compatible with the D5000. I don't know how to use the light meter? I'm brand new at digital SLRs. My 35mm SLR had a button for the light meter but this thing has so very many settings and buttons. I'm lost.

You are going to have to be more explicit in your description of the "manual telephoto" lens.

What model is it?

Did you know that the light meters in the entry level Nikon cameras will not work using any of the Nikkor AI manual focus lenses? If you are using an older AF Nikkor, then you will have to manually focus them, however the light meter will work just fine.

You can find how to get rid of the fEE error on page 221 of your user manual

A f8 with a 2x teleconverter becomes an f16 lens. That requires a lot of light. Mount your kit lens and see what you have to do to shoot at f16.

Skip the converter, set the lens to f8, set camera to manual and iso to 1600. Start with a shutter speed of 1/100 and see what happens.

LEarning how aperture, shutter speed and iso influence a picture is all part of learning the basics.