Look at which syllables are accented.
In a poem, certain syllables are accented in a regular pattern. That's the meter. You just need to figure out which syllables are accented and which aren't and figure out the name for it (if that's what the assignment is calling for).
Types of Meter:
iamb: unstressed / stressed
trochee: stressed / unstressed
spondee: stressed / stressed
anapest: unstressed / unstressed / stressed
dactyl: stressed / unstressed / unstressed
Two roads di verg ed in a yell ow wood
And sor ry I could not trav el both
(The Road Not Taken, Robert Frost; iambic)