I have added my content in Wikipedia, but i have seen anyone can edit the page of others talk...is it really?
I don't know what you mean by 'not safe to add content', but the whole point of wikipedia is that anyone can edit it - they have 'official' editors that monitor and will remove stuff that's offensive or just plain wrong, but loads of stuff 'slips through'.
There's no risks of security or blacklisting or anything like that as long as you are posting relevent, factual information, and/or providing links with such values also. Chuckun