What do I need to stream on Twitch?

I would like to stream it on Twitch. My question is what I need best and how exactly I should do it best

A good microphone and an almost good PC would be recommended. In addition, a good Internet that the quality is good.

Then you may need an overlay and alerts and just things that set you apart

A computer that is powerful enough, a good internet connection, microphone and headphones.

Microphone is also a headset? Or does it have to be a microphone? And a good PC the question is what is good for streaming? I have a work computer an old one from my father that still works fine

There are headsets that have good microphones, but some are of poor quality. From the PC it shouldn't be very old by now, especially if you still want to stream demanding games

Basically, you need 4 basic things first.

a powerful PC (from Ryzen 7, best 2700X or better)
good internet (upload should be at least 6 Mbit)
streaming software such as OBS, SLOBS or XSplit
a good microphone or a very good headset microphone

A facecam would also be recommended here, would be more personal.

Do you really have to stream games? I like to gamble, but I don't play any games that would be suitable for streaming at all

You don't necessarily have to, but if you just do just chatting you need a good cam