Looking at ones hands and doing things with them eg as you did. pushing finger throu, can help to stabilize a dream and can also help get into your brain to accept that you are dreaming which is very important esp if you are new at this. I think you did the right thing by spending time on that. Many start off with that and then move on and do something else (next step would of been to do something like then rub them together briskly or to reach out and start touching and exploring things in your dream).
Ask yourself if you hesitated? hesitation on not knowing what to do next
after you had explored looking at your hands, may of caused you to loose this dream. When one stops and does nothing even just for a couple of seconds while thinking 'what shall I do now?" it can cause one to disconnect from a dream. Hence why I suggest always having a plan of action, a dream challenge you had planned to do if you find yourself in a LD can help.. always have something in mind (even if you dont end up doing it. Try to always stay interacted with your dream in some way.
all I could see in the background was black.
That would of also made it a lot harder to stay in this dream esp for someone new to this as it gave you less to be able to focus on to help yourself stay there. Dont allow the fact that you didnt have anything around you to bother you at all. One dream challenge you could of done even if you are just in blackness is the "What's in my pocket? challenge.. put your hand in your pocket and pull out what you have there. You could of also inspected other parts of yourself, what were you wearing?.
If you dont allow not having any dream surrounding bother you, this situation should right itself after a short while if you do not let it put you off or you can try to create a surrounding by thinking about where you would like to be and imagine being there or another thing you can do is just walk in the blackness, think about it as walking in the dark and that you are about to come to a light, know you will come to a light.
Congrats on your first LD and I best luck with having a longer one next time.