1) A Warning
Communicating in online fora is of course always a good idea to train one's skills to express oneself. The down side is that people tend to use bad language (and sometimes even bad spelling) in (usually anonymous) online communication, even if they are othewise able to write a decent letter or essay. So, for learning a language it could be problematic, unless you are very aware of what people are doing, and use, in parallel, better sources of correct language.
2) A (Conservative) Recommendation
What I can recommend without restriction is reading Micky Maus (that's the German spelling) comics, especially the older ones. The language used there is both educated (in terms of correctness of grammar and width of the dictionary), and still it is everyday, easy-going language with many common phrases used in oral communication in everyday situations.
The long-term translator of Micky Maus in German was Erika Fuchs (1906-2005), active in this job 1951-1988. (https://de.wikipedia.org/wiki/Erika_Fuchs). She got a lot of praise for her texts.
I used Mickey Mouse also for learning other languages, e.g. Bulgarian and Serbian. Big advantage: you find expressions there which simply cannot be find in standard language training text books, and the phrases are used in a concrete situation; which is the essence of understanding them and getting a feeling for their use-cases, much better than just having a translation in a dictionary.
Of course, usually you have to be in the respective country to find the periodcials, sometimes from flee markets etc. For German editions you can use your prefered online flee market.
3) And Anyway A Chatting Tool
For live-communication with Germans online you may try the smartphone app Jodel. This is a tool where people send messages to other users in the same city (or geographical region). This may be asking for a good doctor, or the next 24/7 food store, but also looking for friends, discussing politics, or simply chatting and joking. In my experience, the language used in the chat is relatively good (in terms of spelling and grammar). This is partly so because the tool is used predominantly by university students. In some (provincial, small city) higher education institutions it seems to be used as the general (inofficial) university chatroom. Also there is a forum rule to stay away from offence (clearly offencive statements get marked by the community and then removed by moderators). I think this one is good for learning German. Just register and start a chat on whatever you find interesting.