Its very easy to use, all you do, is before you have submitted your post, right click in the box where you typed, and click 'check spelling', and it brings up a box very much like the Microsoft office spell checker.
I suspect it wouldn't like a lot of the electronics terminology, but if someone wanted to add some common terms to the custom dictionary, and put the file on here for others to use, we would have a lot less misunderstandings, and it would help non-English speakers when posting.
Ron, sorry, I've just got into the habit of asking you lot first!!
*Bows to google*
Ron, also, I agree, shame about grammar, but I did a dictionary extension instead: https://www.thefreedictionary.com/add2ie.htm (which has a built in encyclopedia function). Anyway, in my experience, most grammar engines are awful.