To hide all of your personal information when creating a listing, just do the following:
1. Answer "NO" to the question "Include Profile with Listing"
2. Do not enter your street address or phone number on the listing
This will keep all of your personal information private.
Someone interested in your listing will be able to contact you via anonymous email using the "Contact Advertiser" link on the site. The email address you enter for a listing is NOT shown on the site - it is used by the site to route anonymous contact requests to your email without making your email address visible to others.