There are different methods to import data according to your needs:

• web-services: if your data must processed before being uploaded to OpenERP, you may have to write a script (or use an ETL) and import your data through the web-service API
• SQL: you can still create your records directly in PostgreSQL but this method is not recommanded as constraints are not validated and you may break the system
• CSV file: save your data in a CSV file and import the file through the user interface

I will describe the "CSV File" approach which is the simplest one. To activate the import feature, you must go to the menu "Settings > Configuration > General Settings" and check the option "Allow users to import data from CSV file".

Once it's activated, you have an "Import" option above all list views. As the contacts appears by default in the kanban view, you must first switch to the list view using the top right icon.

The import wizard is pretty simple. If you have questions, there is a FAQ in the bottom of the import wizard.