To import using the Node Import module:

  1. Create the content type in CCK that you want to import into. Set up a field to store each value you want to import.
  2. Install the Node Import module.
  3. Select the option to import from admin >> content >> import.
  4. Upload the csv file and proceed to mappings.
  5. Map the fields in the csv file to your CCK fields.
  6. On the next screen you can set default values for any fields that are empty in the csv file.
  7. You will next see a preview of your imported data. If it looks OK, go ahead and import it.

Here's the description of how CCK imports work:

/**
 *  CCK data can be imported into any column of a CCK field.
 *  Most fields have a 'value' column, but there are others that 
 *  can be used, for example:
 *   - Textareas have a 'value' and a 'format'
 *   - Date fields have a 'value', if date-specific timezones are
 *       used they also have a 'timezone' and 'offset'
 *   - Nodereference fields have a 'nid' column
 *   - Userreference fields have a 'uid' column
 * 
 *  For nodereference and userreference fields you can either import the
 *  numeric value for a nid or uid, or a text value for the title or
 *  name. If a numeric value is imported, it is used as is.
 *  If a title or name is imported, the module will search for 
 *  the nid or uid that goes with that title or name.
 * 
 *  Date values can be imported as unix timestamps, as ISO values, or as
 *  any text that can be interpreted by the php strtotime function.
 *  The date 'timezone' column expects a full timezone name like 'US/Central', 
 *  timezone abbreviations are not unique and will not work.
 *  The date 'offset' column is the plus or minus value in seconds.
 * 
 *  Multiple values can be imported into any CCK field that has multiple 
 *  values enabled by separating the values with a double pipe (||).
 */