Raise the back of your tongue to touch the soft palate (velum). Stop the air, then release.

Americans pronounce casually as KA-zhuh-lee (/ˈkæʒəli/). Stress falls on the first syllable — keep everything else short and quick. You'll hear it in sentences like "Usually casually" or "Conclusion of the occasion was casually done" — more examples below.
Record yourself saying "casually" and play it back. The mic stays on your device — nothing's uploaded.
3 syllables, 6 sounds. Tap a syllable to jump to its row, then explore each sound's mouth shape and how it's made.
The textbook way isn't wrong — it's just not how anyone actually says it.
Stress falls on the first syllable, not the others. Stretch KA — keep everything else short and quick.
Don't pronounce the first syllable too fully. The unstressed syllable reduces to a schwa — the lazy "uh" sound — in casual speech.