Raise the back of your tongue to touch the soft palate. Add vocal cord vibration, then release.

Americans pronounce guy as GAHY (/gaɪ/). You'll hear it in sentences like "Why did the guy deny the lie to my eye?".
Record yourself saying "guy" and play it back. The mic stays on your device — nothing's uploaded.
1 syllable, 2 sounds. Explore each sound's mouth shape and how it's made.