Hi @diewelle welcome to Steemit!! The formatting tool already programmed into Steemit is called Markdown! That's what is built in whenever you go to write a post so it's just simple coding that enables you to manipulate it to be centered, bold, italic etc. It took me a while to learn but all of my posts have to be done individually by hand (and it takes me hoursssss lol) I am sure if you search how to format a post will come up that can teach you instead of me trying to explain it all here but if you need more help, feel free to message me =D Good luck!