It takes time.
ha ken larn english good
Ha- this should be HOW
ken- this should be CAN
You missed the word 'I'
larn- this is spelled LEARN
english- this has a capital letter- English
good- this should be WELL:
How can I learn English well?
By practising, as you are. You have got some knowledge- start posting here and you will start learning. Welcome to UsingEnglish. ;-)