I Need Some Help

So we all know that mibba is for people to share their stories. Well I've been on this site for a month or two know and I haven't written a single story. I want to do a fanfic but I feel like it wouldn't turn out well. I want to try writing an original fiction but I'm not sure if I can come up with a good enough plot, details, characters for the story. I like to think of myself as a good writer and I have been told that I am good but how can I be sure. I really would like to post a story to get some feedback but I wanted some input on whether or not I should go ahead and give it a try.