To apply for an SSS UMID card as an OFW, you need to be an SSS member and have a valid SSS number. Start by filling out the UMID card application form, which you can find on the SSS website or at your nearest SSS office. You'll also need to provide valid identification. After submitting your application, the card will typically be sent to your registered address or can be claimed at an SSS branch. For more details, check the SSS official website or contact their customer service.