Here's a splendid little mnemonic rhyme about the metrical feet, written by a great English poet, Samuel Taylor Coleridge. Memorize it!
Trochee trips from long to short.
From long to long in solemn sort.
Slow Spondee stalks, strong foot!, yea ill-able.
Ever to keep up with Dactyl's trisyllable..
Iambics march from short to long,.
With a leap and a bound the swift Anapests throng..