Open Office?Please Help?

ok when i make a typo that a realized that i made after my essay that i typed in open office when i click in the middle of a paragraph it highlights a word then letting me type a letter between. i Kno theres a key to fix it or mabye in the options i tried looking in help but i dont know how to explain it. I just wanna type in Open office without restarting EVeRYTHING i type. Thanks First to answer correct will be best answer xD