Here is a useful video that demonstrates the correct pronunciation of phonemes. Please refer to this as much as possible to begin to support your child as they develop their understanding of phonetic sounds. As children progress in their phonic knowledge, they will begin to use this to then identify sounds in decodable words, learning to segment and blend.
Jolly Phonics Letter Sounds (British English)
Listen to the 42 letter sounds of Jolly Phonics, spoken in British English. Each letter sound is clearly spoken twice, before an example word is given. Perfect for parents, teachers and children who aren't sure how to pronounce the letter sounds.