You can add your product options in PRODUCT_OPTIONS field in your import file. Please take a look as this is done in sample file. You have to follow the same format to be able to import your options. You can have a n unlimited number of options specified for each product in this field but format has to be exact. Also, has to be unique for import to work. Here is example of PRODUCT_OPTIONS field for option called "Cover" which is shown to the customer as "Choose cover type" with selection : Soft, Hard (+$5)
CoverChoose cover typeYY0
Or you can add options aftert the import in Modify product -> Product options.