Researchers regularly receive – directly or indirectly – 'calls for papers' , which means that yours will have to be catchy, neat and informative if you want to attract their interest.
It should indicate in the clearest way:

• aim of the conference
• format of the conference (symposium, workshop, round-table, etc.)
• issues to be covered
• date and venue
• length of papers
• deadline for provisional titles and abstracts (as well as a word limit)
• address for submission
• fees (if any)
• scholarships (if any)

As to its dissemination, it should be sent to

• academic departments and centres dealing with the subject of your conference
• specialized mailing lists and newsgroups