I need some help with black

I need help playing as black. Whenever I play black I kind of just move and attempt to castle and set up some variation of modern defense. This playstyle is alright but isn't exactly good. I play even worst when somebody plays d4 and I have no idea what to do. Can someone help?

1. e4 e5
   or
2. d4 d5

Don't waste time for other openings.

d4, d5 or e4, d5, find a Scandinavian guy.

You can play Albin's countergambit or Indian defense.

What kind of help do you want?

Do you want lines? (Do you know chess notation?)
Do you want links to resources?
Do you want tips?

How exactly can we help you?

Against all d4 openings you could play 1. d5 2. e6 3. c5 It really isn't stylish to play the Tarrasch these days, but it develops very quickly as you're going to get in Nc6, Nf6 and Be7/d6 or b4 depending how white arranges their material. What makes it good is you can do the same thing against 1.c4 by changing up the move order to 1.e6, 2. d5 3. c5. It should be noted you can play this against any non-1.e4 system as well.

Though to be honest more people will recommend a system opening like Slav or Semi-Slav. Be prepared though that those openings have theory past 30 moves though so you better know it like the back of your hand. I played it up to 1800 OTB USCF but you need to memorize a lot of moves/plans.

I find people just know less about the Tarrasch these days even if there are some positional lines where black can suffer. It is pretty rare people actually know those lines. Also if you one day play over the board chess and people start booking up on you can switch off between it and say the queen's gambit accepted with the same starting move. This gives you some flexibility in systems later in your chess career. Before the Tarrasch I hated playing against 1.d4 because it feels like I was playing myself as a d4 player.

Against 1.e4 if you want to go simple Caro-kann is pretty easy setup to learn. You'll get more winning chances with a more dynamic opening though. These days I enjoy 1.Nf6! Once again people do not play it all the time at the top level but the system has been used extensively by GM's and is annoying for an unprepared opponent to meet. Very rarely do these two systems net me a situation where I feel the opponent has superior opening knowledge. When you hit tricky areas turn on stockfish after the game and see how it handles those positions. You'll find you have very interesting counter play in all lines I've listed and you can continually get better and better at openings others will just find annoying to play against you once your opening knowledge reaches a certain level. Better still is you will become familiar through more experience with the middle game positions where your opponent is likely to have no idea what their plan is.

Feel free to choose other openings too. Rarely is the opening actually the problem, it is the lack of study and examination of resulting middle game positions that get people into big trouble.

You can start by playing defensively (by grouping pieces close to each other) and especially avoid exchanging pieces

@Bee3D said in #1:

I need help playing as black. Whenever I play black I kind of just move and attempt to castle and set up some variation of modern defense. This playstyle is alright but isn't exactly good. I play even worst when somebody plays d4 and I have no idea what to do. Can someone help?

Go for the principles.

1. bring the pieces out
2. bring the king to safety
3. fight for the center

Done. No need to memorise any openings. Because the theory lines of any opening somehow will include these three principles. If you have learned these, you have covered let us say 75% of all openings and you will understand later better the openings.