If you want to produce any English speech sound correctly you want to get your placement right. The /th/ sound is produced with your tongue slightly protruding from your front teeth. Your upper and lower teeth will come together on your tongue. It will be much easier and beneficial for someone to show you the exact placement rather than reading text instruction. However, there are some videos online that will show you if you Google it. Another good idea is to practice the /th/ sound in isolation with a mirror so you can see and feel the placement.
Student or Learner