Lift your bottom lip so its inner edge (where the wet part meets the dry part) touches the very bottom of your top front teeth. Add vocal cord vibration as you blow air through.

Americans pronounce viewing as VYOO-uhng (/ˈvjuəŋ/). Stress falls on the first syllable — keep everything else short and quick. You'll hear it in sentences like "Choose a smooth route to the moon viewing".
Record yourself saying "viewing" and play it back. The mic stays on your device — nothing's uploaded.
2 syllables, 4 sounds. Tap a syllable to jump to its row, then explore each sound's mouth shape and how it's made.
Lift your bottom lip so its inner edge (where the wet part meets the dry part) touches the very bottom of your top front teeth. Add vocal cord vibration as you blow air through.

Start with the tongue mid-front raised high, almost touching the roof of the mouth (but not touching). Glide into a tight lip circle as the tongue back lifts.
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 VYOO — 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.