All the "A" class vowels are pronounced with an "ah" sound. Vowel length is indicated by the nikkud which accompanies each consonant. In modern Hebrew there is no differentiation in vowel length for kamats and pataḥ.
The ḥataf pataḥ only occurs with the
guttural letters [א ה ח ע].
"A" class vowels are usually transliterated as "a".
Practice. ...Putting things together.
Listen to and practice saying these consonant-vowel combinations. Each combination, whether open or closed, represents a syllable.