how can i learn tajweed?
Tajweed and its application can only be learned with a qualified teacher.
The rules themselves can be studied independently, but their correct application can only be done by listening to, reciting to, and being corrected by, a qualified teacher of the Qur'an.
I want to learn to recite the Qur'an with proper tajweed, but don't know where to start.
The first step is finding a qualified Qur'an teacher who will listen to you and point out your mistakes, and help you practice fixing them. You will need to learn the Arabic letters and vowels too.
What if there aren't any qualified teachers where I live?
Then your task is going to be a little harder, but certainly not impossible. You need to work with tapes of good reciters, for example, Sheikh Abdullah Basfar, or Sheikh Mohammed Hosary. There are sets available on the Internet and in Islamic stores that are called "mu'alm". In these sets, the reciter reads a phrase, and then there is a blank space on the tape, allowing the student to repeat what the reciter has just read.
You will need to work on the pronunciation of letters by getting a description of the articulation points and practice placing your tongue, lips, or finding the place in your throat where the letter is articulated from, and compare it to the letter when recited by the Sheikh.
There are many online teaching programs now available. Some free, some for a fee. If you do an online search with any of the search engines such as Google or Yahoo or other engines, you can write in the words: online teach tajweed and insha' Allah will fine many different programs available.