One of the most difficult things in English is pronunciation. Correct pronunciation is the basis for good communication skills. Here is a little help which I found very effective:
www.stepls.org/pronunciation
Please feel free to comment if any doubts or questions occur.
Enjoy!
You can find some help on the link below to practice the correct pronunciation of the sound "th" in English :)
https://www.stepls.org/pronunciation-th
Good luck :)