I want to know what do you guys use to make a artwork?
Do we need a required application?
Or I can just draw in a piece of paper and post to at my social media?
If you are talking about ann threads it's not artwork but BBCode. However within a thread or post you can have artwork in the form of pictures or ascii code, etc.
There are some helper apps, just google BBCode editor and see what comes up.
Most people just use the built-in forum function with the existing toolbar.