Hello Kevin Lee,
Here are some tips to help you learn English .The time you need to improve depends on how much time you dedicate to learning and how intensive your effort is.To learn 'quickly' you have to intensify your efforts like taking intensive courses for examples.
-To start learning English from the scratch you might need to take some initial classes to learn the alphabet , how to pronounce ,basic vocabulary and grammar. You can do that by taking classes in a language institute or by self learning online, although some guiding from a tutor at that early stage is recommended, unless you are able to depend only on audio/video facilities.
- Then you have to practice and increase your vocabulary through different means such as :
*Reading at your level of comprehension simple texts or books and looking up new words .
* Listening to English through music and possibly reading the lyrics .
* Watching movies in English with subtitles in your mother tongue.
* Chatting with natives online using voice chats or in real life .Mingling with natives is a very good way to be constantly listening to speech in English, even if you don't understand at the beginning.