The difference between č, dj, and dž?
They all sound similar, so how can you tell the sounds apart?
As you haven’t got any answers yet and have downvotes, and in spite of this being something I do not know about, here at least are some videos to get you started - they may not cover quite what you want, but perhaps they will lead you to more suitable ones:
The Czech Alphabet: https://www.youtube.com/watch?v=JO-6CsEH9FA
Czech alphabet - general phonemes and pronunciation: https://youtube.com/watch?v=Dot3LVAeABc
And if IPA is any use to you: https://en.wikipedia.org/wiki/Czech_phonology
By the way, the downvotes are probably because this isn’t in the Czech specific forum. I have made a presumption the question was about Czech.