The difference between č, dj, and dž?

[Lemniscatarum]

They all sound similar, so how can you tell the sounds apart?

[SprightBark]

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.