The other day I was thinking of challenging my writing skills by trying to "fix" the horrible mess that is Jeff The Killer. (Note that I realize that I can't really replace the damage that has been done. Nor have I something against its original creator. I'm just doing it as a fun little prompt for myself.) With that being said, I don't think I will even upload it on the wiki, since it is by no means an original pasta and will get deleted as soon as I post it. But if you'd like me to, I can upload the draft here for beta testing and editing and then post it on the writers' showcase when it's done.
I wouldn't waste your time on this silly gimmick. I can see you've never posted a story here in the first place. Why don't you go over to the writer's workshop and post an original story there and engage in the learning process with other writers. You can offer feedback on other people's stories and also take the time to improve your own.
If you really want to challenge your writing skills, you can always message me and I'll come and review your story. I'm not a very tactful person, and I don't go into my reviews looking to give praise, but if you're committed to writing and getting better you'll find my reviews insightful and helpful and honest. I'm not mean-spirited, but I am quite forthright.