@thanhvannguyen944 there are some good videos on Youtube that help explain it, but otherwise it's just practice, practice, practice!
Just a random tip: something that helped me a lot was learning about the IPA for pronunciation help.
You don't have to learn the whole thing, just the symbols and sounds that make up french phonology. The following pages might be helpful:
Most dictionaries will give the pronounciation of words in the IPA, and I've
found this invaluable for learning how different words are pronounced.
Hope this helps! :)
Out of those features, it was the reading and listening exercises that I used the most. For a phone they are extremely useful since you can then practice listened to or reading the language wherever you are.
A nice enhancement request as well: would be nice if it were possible to mark some listening/reading exercises to be available offline. I just noticed that it looks like the app works offline now too, which is great! I like apps that work offline to save my data while I'm not on wifi. :)