First congrats! Photography is amazing and is extremely rewarding. Also go Nikon!! (Canon is great to though ;D ). I will try to keep this as short as possible because I could go on for days.

So for portraits you would probably want to get the 50mm prime 1.8f lens (my pref). This is because in portraits it's very aesthetically pleasing for the person or persons to be in focus and the background to be very blurred. This draws the attention to the people (usually what you want).

For nature, it depends if you want to shoot animals or landscape, because animals require telephotos and landscapes reply or wide angle. A good general telephoto lens is the 70 to 300 mm. It's cheap and is a great way to get your hands dirty. Also get a tripod, it really is the most overlooked tool to photography. For you a 50 dollar one from Walmart made of aluminum would do great.

Important thing for you also to remember is that when you're buying lenses, if they are for the FX sensor which you don't have, (you got the DX sensor) you have to increase their focal magnification by 1.5. So that 50 is really a 75. Which is an amazing distance for shooting people too. (Farther away you are the prettier the people, as a general rule of thumb. And I'm talking around 10ft not 100)

Onto the Photoshop. So the interesting thing about Photoshop is you pay for it monthly. They did this to prevent it from being illegally downloaded like it has been in the past. However Photoshop is extremely well, though it can get very technical. The one I use is Pixalmator (for Mac). It was $30 total and does a great job for my needs. However there are probably 100 different editing software is out there, so it is all on what you feel the most comfortable with.

For the business aspect which also ties into how to get your name out there, start with Facebook and a website. Wix and Wordpress are both very nice website creating companies, check 'em out. The reason I mention Facebook is because when your first creating it you can invite all your friends to like your page which immensely gets the ball rolling and helps. On that Facebook page make sure to put your self in the local company category, which will allow reviews and ratings to be shown.

You can PM any other questions you have!

Again welcome to photography and I wish you the best of luck!!

Sorry ahead a time for any grammar or spelling mistakes it's 1 am cut me some slack.