Introductory guide to poetry?

I would suggest two purchases:

Norton Anthology of Poetry - Margaret Ferguson, Mary Jo Salter and Jon Stallworthy

(Current is 5th edition, I think, but you probably can pick up older editions cheaply enough)

&

The Poetry Toolkit - Rhian Williams

Depends if you want to read poetry or write poetry. Get Ted Kooser THE POETRY HOME REPAIR MANUAL. Do not get Norton or some comprehensive anthology. There are so many speciality anthologies out there, one on jazz poetry, one on motel poetry, one on parents. Why don't you try Billy Collins 180 Contemporary Poems. It is even on line and free: http://www.loc.gov/poetry/180/

Lots of free contemporary poems to find the ones you like.