It's a little hard to understand exactly what you're asking (sorry to tell you, but your grammar is sometimes chaotic), but I guess the word you want is "properly". "Could you write properly, please?" That would mean following a standard and paying attention to the usual things like spelling and so on. There are many more colourful ways of asking this, but a nice "could you....please?" request is diplomatic enough.

I believe before you should make any rude comments like that, you should make sure that there are no mistakes at all on your side. And even provided there are no mistakes on your side, to make a rude comment to somebody who is learning a new language will only discourage him/her to keep learning. Maybe you could politely let this person know which mistakes he/she made and this way you are polite and helpful. Having said this , I believe there are minors on this site too , so please watch your language in future.