Can you scan some lines from "Ode on a Grecian Urn" (Stanza 5, lines 6-10)
The final five lines of "Ode on a Grecian Urn" that you list are predominantly iambic pentameter: ten syllables per line, five metrical feet, iambs predominant.
All but the fourth line would be scanned like this:
with the - representing an unstressed syllable, and the / representing a stressed syllable. Each iamb (-/) is a metrical foot, so a vertical line would be placed after each iamb to mark each foot.
The fourth line is a variation. If you check your dictionary you'll find that "beauty" is stressed on the first syllable, not the second. Thus, the speaker uses a trochee to begin the fourth line. It would be scanned like this:
/- -/ -/ -/ -/
A speaker usually alters the rhythm to add variation and for emphasis. Here the key line, his main point, if you will, is emphasized with a trochee.
I'll let you or another editor figure out the rhyme scheme, except to say that "all" goes back to the line before the lines you quote, and that in this poem, "say'st" is intended to rhyme with "waste. That should enable you to figure out the rhyme scheme.