Start with taking pictures of dark objects around you.
All experience I have with star photography is accidentally: I was making night photos and there were stars in the photo. I found it funny to see what most people on this community probably know: stars move so fast that you will get strips if you expose for more than a few seconds. So my answer won't be the best you can find, but given that you didn't get another answer yet it will be the best one for now. Hope it helps you.
With my experience, I would start with normal night photography to get a feeling of your settings. Back in the days my camera was so noisy I was used to only shooting at ISO 100. You claim you used the maximum aperture, but I think you mean the minimum. A F value of 5.6 sounds like the biggest you can make the hole in the diaphragm, that is the F value cannot be smaller. It sounds like a good value to start. Now go to bulb mode: you probably have to click twice: one to open and once to close. The disadvantage is that both times you have to touch the camera thus shaking it, but that's of later concern (you can work around that with a remote or a timer delay). Now try to keep the shutter open for 1s, 2s, 4s etc, go up to 64s. Just aim at a tree or so. If it is to dark for autofocus, just focus by hand. You are trying to find the right shutter speed, not aiming for crystal clear tree pictures.
I expect you photos at 1s will be too dark, but somewhere before 64s you will be able to see a lot more than with your naked eye. In my experience, if you can see the trees with your naked eye, and you can see the stars as well, the exposure for the stars will be the same order of magnitude, so now it may be time to aim the camera upwards. If the photo still turns out black, it may have to do with focusing. Otherwise it may be that you don't use a tripod and the stars are never in the same place for long. Still you can apply the same technique: double the exposure time until you start seeing some details.
One you get the exposure right you can start varying: increasing and decreasing ISO, aperture and exposure time (shutter speed).