Translation:I am happy to notice that you are doing a lot better.
How are you doing? How's it going? both are used in English. We cannot translate word for word. The expression in French uses "aller".
If you want to ask "What are you doing?", use "faire":
Well, as I've said before, the hints are not at all trustworthy. "You are going much better" sounds very odd to most English-speakers, although someone in the above discussion says they say it in Australia. It is not what I'd call conventional English, in any case.
It is possible, in an extremely casual situation, to ask, "How's it going?", meaning "How are you?" and for the reply to be "It's going quite well." But in North America, at least, you don't hear "How are you going?"
My sympathies. I am endlessly impressed with the students here who are attempting to learn French via English when neither is their first language. I'm sure it must be very difficult.
I do think those hints should be discarded, they frequently mislead people.
The dictionary at http://www.wordreference.com/ is a much, MUCH better resource.