You must export your database from THIS site, and then bring all your information into that database, making sure to copy the information to the right fields.
If you have a custom field, make sure you enter the data there to match EXACTLY the options that you created when you created the custom field.
If you are importing a database with a custom CHECKBOXES field, separate the different checkbox answers with a comma. Don’t add spaces in between the words and commas, just put a comma between the answers like this:
Spaces are allowed WITHIN the answer, but no spaces BETWEEN the answers.