Inserting a new SD Card will not work, it needs to be properly formatted and programmed. You can do that with Sentinel by using the "Clear User Data" command in the HomePatrol menu then updating and writing the database and your Favorites Lists the the SD Card.
If this is beyond your abilities then perhaps it might be best to purchase a pre-programmed SD Card from Scanner Master or another dealer. See
SD Card Upgrade for Uniden Database Scanners | Scanner Master
These cards are all set to pop in the radio and work out of the envelope. While I always encourage people to program their HomePatrols themselves, if you do not have a Windows computer or otherwise are not able to do it yourself, then paying someone to create it for you might be a better alternative. You can also see if there is another scanner hobbyist in your area who can help you program your card.
Good luck either way!