How to remove auto-correction from iPhone?

I dont know why but whenever I type on my iPhone it is soo hard to get a message or paragraph spelled correctly . I don't want to have to use spell check or keep erasing the words to respell !! Its sooo annoying ! I know what I am trying to write and i know how to spell but almost every word I type its wrong .. so instead of it being typed in 10 secs it doesn’t get done for like 2 minutes because I have to keep erasing and retyping it correctly !!! ???

[Re-Titled by Moderator]