Welcome to the addiction, er, uh, fun--yeah, that's it--fun... of photography. And welcome to the Forums.
1. Read the manual. It will be dull, bore you to tears, but read it anyway.
2. Buy a book made by someone other than Nikon talking about your camera. A D70 is very old so you should be able to get a good used book. It's not that Nikon manuals are crap (they're actually quite good, it's just that most technical manuals are boring and dull), it's that another book written by someone not being paid by Nikon will offer judgments and recommendations and talk about how they use the camera. You'll learn a lot from that.
3. Go shoot. Shoot a lot. And then review your photos. And then go shoot some more. And review some more. And keep shooting. Never conclude "oh this is crap" and then delete. Instead, at every photo look at it and ask "why did it turn out this way?" and look at what you can learn from that shot (whether it was good or not). Do not look for popular appeal...people may like your work, they may vomit at your work and none of it matters at this stage. There is a great line from the great photographer Henri Cartier-Bresson...."Your first 10,000 photographs are your worst." So start a shooting so you can get to 10,001. And then 10,002. Oh, and when you hit photo 1,000, go back and read that dull, boring manual again--there was stuff that made no sense or that you passed by when you first read it that will now be critical once you have a couple of thousands exposures to your name.
4. Go get a book by someone like Bryan Peterson that will explain more about composition and seeing photographs before you ever pull the camera up. I recommend Peterson b/c he writes for all levels (so you can read him as a beginner and then get more of his stuff as you improve). Also, he's prolific so if you like his writing style and it's clear to you, you can buy other books by him and you won't feel like you got ripped off. Finally, he also does videos for
Adorama TV so if you like the book a lot, you'll know you can turn to his short videos and they'll work for you as well. Michael Freeman is another good guy who is prolific and covers topics that won't be in the manual (b/c they're less about how to use the camera and more about composition, creating a photo vs. taking a picture).
5. Ask questions here on the Forums. And share your work asking for C&C. Most of the time we're extremely friendly. And when someone is an a-hole to a newbie, the rest of us usually shoot him down.
Just a couple of other things. Some people who don't know sh*t will laugh that you're using a D70. It is an old camera. I still have one (as a backup). Big, a bit clunky, technology has improved since it came out and low light performance is mediocre. That said.....D70's have a rep as being very reliable beasts (I never had an issue with mine.) They came out when Nikon was trying to get back in the game with the prosumer market. As a result, they have unlimited sync speeds for speed lights (which will mean nothing to you now but as you progress will be a nice plus). And frankly, 90% of what a good DSLR can do (in terms of technology) is stuff that most serious photographers rarely or never use. The best camera isn't the one with the most bells and whistles, it's the camera who have with you that you can use effectively. A D70 is a heckuva great camera to start with. My favorite all-time quote about photography is by the great Dorothea Lange. She once said: "A camera is a device to teach you how to see without a camera." Folks who don't know what they're talking about will claim that good cameras take good photos (as if a restaurant produces great meals b/c it has a great oven). No, you get great photos b/c you have a great eye and then you learn how to manipulate your tool (the camera) to produce what you want to create. So what you're looking to do at this stage is to:
--have fun
--learn how the camera works (i.e. become competent)
--learn about photography (like composition and color and light and exposure speeds and a bunch of other things that are fun to manipulate, that are the difference between taking a snapshot vs. creating a picture).
--discover what aspects of photography you enjoy the most
After you do those things, you'll be in a position to say what you want to upgrade to and what you're trying to shoot. Until then, your D70 will do you just fine