how do I start playing as black

how do I start playing a random player as black

Simplest and best is to defend 1 e4 e5 and 1 d4 d5.

Its always white who does the first move, never black. Or I havent understood your question.

How you want to handle the opening is up to you. The best first moves with white are probably 1. e4, 1. d4, 1. Nf3 or 1. c4.

After that first move, no matter what side you play, you have to react to whatever the opponent is doing, ideally by not just defending, but also by making as many threads as possible on your own, developing your pieces, grab space especially in the center, bring your king to safety, start attacks on the opponents king, etc.

For example as black you could just decide what you like to play against the first move from white. Like for example you could decide "I'll play 1. e4 e5, 1.d4 Nf6, 1. Nf3 d5, or 1. c4 e5 with black". This makes it much easier to play the first move fast, but of course also makes you much more predictable.

You should still aim to follow basic opening principles. Develop your pieces actively, control the center and prioritize king safety.

Dude...ixnay on the ackblay thing. Peeps in here are sensitive and s**t