An ä is not a sound that native English speakers make. It is not a short a like in “catch”. It is not a long a like in “made” either, though that is slightly closer. To me the closest vowel sound in English is a short e like in “end”.
The ch part is also not an English sound and it was harder for me to learn than ä. “ch” is sort of like how you would immitate a hissing cat. It is on the roof of your mouth in the back. That’s the best I can describe.