There isn't currently a built in ClassiPress function for importing (only the default WordPress tools), so at this stage as far as I am aware, the methods that customers have used have been via the
WP tool or a plugin which does half the job. It brings the posts over to the site which is the first step. However, from there a custom sql query is required to then convert those existing "Posts" over to "Ads".. same applies to categories.. These need to be migrated over from "Categories" to "Ad Categories". This is because ClassiPress uses
WP custom post types and taxonomies functionality.
There are plans in future to implement a .csv importing tool, but we have no confirmed information on this yet.