To enter online (preferred), visit the online submissions manager and be sure to choose "Barthelme Prize for Short Prose" as your genre. Upload up to three previously unpublished prose poems, short stories, or micro-essays, each no more than five hundred words in length, all together in a single file. Do not include a cover letter, your name, or contact info of any kind in your uploaded document; please put this information in the "comments" field.
Once you've clicked "submit," you will be redirected to PayPal to authorize your $18 online reading fee, which also gets you a one-year subscription. You won't need a PayPal account, only a credit card. Multiple submissions are acceptable, but you must pay the fee for each entry, and you will only receive a single one-year subscription or renewal regardless of how many entries you submit. All entries will be considered for publication, though only one will receive our $1,000 prize. We'll contact you if there are any problems with your payment; please do not email us to confirm whether payment was received.
To enter by mail, send up to three previously unpublished prose poems, short stories, or micro-essays, each no more than five hundred words in length. Your name and address should appear on the cover letter only. All entries will be considered for publication, though only one will receive our $1,000 prize. Include an SASE for results. Manuscripts will not be returned. Your $15 postal reading fee, payable to "Gulf Coast," will include a one-year subscription. Multiple submissions are acceptable, but you must pay the fee for each entry, and you will only receive a single one-year subscription or renewal regardless of how many entries you submit.

Send Postal Entries to:
Gulf Coast Donald Barthelme Prize
Department of English
University of Houston
Houston, TX 77204-3013

http://www.gulfcoastmag.org/
http://www.gulfcoastmag.org/index.php?n=7

Click on the link above and go to the contest official site