Let me recommend a few books written by poets that introduce one to various aspects of writing poetry:
Addonizio, Kim and Dorianne Laux. The Poet's Companion: A Guide to the Pleasures of Writing Poetry. This book covers a wide range of topics including potential subjects such as grief and love (and also includes a chapter specific to erotic poems); craft elements such as image, metaphor, and form; comments on other elements of the writing life such as writer's block and publication; and suggestions for further reading, both of poems and of instructional material.
Kooser, Ted. The Poetry Home Repair Manual: Practical Advice for Beginning Poets. Not as focused on technique as some of the other books, the chapters cover topics like "Writing About Feelings" and "Working with Detail." Kooser is a Pulitzer-winning poet.
Oliver, Mary. A Poetry Handbook: A Prose Guide to Understanding and Writing Poetry. An excellent introductory guide by an award-winning poet (Pulitzer, National Book Award).
Oliver, Mary. Rules for the Dance: A Handbook for Writing and Reading Metrical Verse. Another basic introduction to writing poetry by Oliver, one that focuses on formal verse (rhymed, metrical) rather then free verse.
A couple of essential web sites containing articles on poetry, on poets, and both featuring a wealth of poems by classic and contemporary poets: Academy of American Poets and The Poetry Foundation.
Everything I've ever read about learning to write poetry stresses reading lots and lots of poems. Since you express an interest in erotic poetry, here are some examples I've posted from this thread, along with my comments:
These examples all happen to be written by female poets, but that probably just reflects my personal bias. I tend to more often find erotic poems written by women (straight or gay) more interesting than those written by men. Not sure why, as one of my favorite poets writing erotic poetry here on Lit is the (now departed) darkmaas, who is male (or appears to be, this being the internet).
My advise? Listen to Mc's (storm, wizzkid) or Irish limericks. Learn to feel what you want to say, then make it rhyme. don't force it, nurture it. I hope that helps, but this is only one persons ideas (example.. I was once a man on a forum, who would like learn how to be in a foursome, to lick a girls clit, whilst she's sucking my dick and getting banged from behind whilst she's smiling) ok that a threesome but you get the point;-)