They also invented spell check.
Sentences begin with capital letters and end with punctuation marks. Who is they? What does that sentence try to communicate?
Read what I wrote about taking a minute and thinking man. It only costs you a few seconds and makes communicating with and relating to people much, much easier. Give it a shot. Accept that you can be wrong, and that there's nothing wrong with that, because everyone is sometimes. That's your first step to really growing up. You'll be mature when you stop trying to show and prove how mature you are. What you're doing now just makes you look ignorant and childish.
Take a second and think, plan and review in your head before you type, or speak for that matter. It'll do you a world of good.