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

Americans pronounce cascades as ka-SKAYDZ (/kæˈskeɪdz/). Stress falls on the second syllable — keep everything else short and quick. You'll hear it in sentences like "The waterfall cascades down the side of the cliff".
Record yourself saying "cascades" and play it back. The mic stays on your device — nothing's uploaded.
2 syllables, 7 sounds. Tap a syllable to jump to its row, then explore each sound's mouth shape and how it's made.
Place your tongue tip near the roof of your mouth behind your top teeth. Push air through the narrow gap. No voicing.

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

Start with your jaw slightly open and the front of your tongue forward and slightly up. Glide upward, your jaw closes a little more and your tongue arches higher toward the roof of the mouth.
Touch the tip of your tongue to the roof of your mouth just behind your teeth. Add vocal cord vibration as you release.

Same position as S, but add vocal cord vibration. Feel the buzz.

The textbook way isn't wrong — it's just not how anyone actually says it.
Stress falls on the second syllable, not the others. Stretch SKAYDZ — keep everything else short and quick.