In the step "publication channels" you can choose the publication channel you want : widget iFrame, minisite, Facebook page, mobile site.
Choose "minisite" and then select the site on which you want to publish your campaign.
Determine the date and hour of the beginning and end of your campaign.
Validate this publication channel and add new channels if you want to.
Remark : in order to add a minisite you have to go to "parameters"