We make the sound in "hot" (/a/) with our mouth open the widest. Pretend you are going to the doctor and saying "ahhhhhhhh".
See how open your
mouth is and how
far back your tongue is.
The sound in "ought" is made with your mouth open not as wide and the sound more in the middle of your mouth. Try to say a very quick, light /ou/ sound. That is the sound in "ought".
Don't worry if you are having problems with this sound! Many native English speakers do, too! New Yorkers pronounce the word "ought" much differently, and many people in the mid-west pronounce the words "caught" and "cot" exactly the same.
Now let's listen to some sounds!
To practice more with the /a/ sound, go to this page: