To pronounce “deny”, start by making a /d/ sound with your tongue on the roof of your mouth just behind your teeth. Next, make an /e/ sound as if you were saying “egg”. Finally, make a /n/ sound with your tongue on the roof of your mouth just behind your teeth, slightly nasalizing it. The IPA transcription for “deny” is /dɛˈnaɪ/, where the /ɛ/ sound is similar to the “e” in “set”.