Save it in tab-delimited format, that would probably work best for the import.
In order to make the import as smooth as possible I would do this:
1. Add all the Nanacast field names to the top row of your spreadsheet (see screenshot). Then make the spreadsheet data reflect what those fields are. Then when you import it will be easy to match up the fields.
2. When you finish, copy the spreadsheet to a new file and remove all but 1 or 2 rows, or just have yourself in one of the rows and then test the import.
3. Check that you got the email and make sure you get into your memberlock blog. Check the client record in Nanacast to make sure the billing info is correct.
Keywords: Import members