Hi Soviseth,
It always happens to non-native speakers of Englsih like us. It is only 40 percent that you can listen to a foreinger. Listening is a cumulative process, something you have to develop days after days. You should not expect to be very good at it at the beginning. When you want to be able to listen to it, listen to it more.

I'd like to suggest you to improve your reading, vocabulary, writing, speaking while you are listening. And I'd prefer you to learn a text book with an English cassette to listen to because this way you can read and listen to English at the same time and repeatedly. Please learn to have a good pronunication by listening more to the native speakers of English.