If you need help with updating your device to Lumia Denim, you better check our preparation and update “How to prepare & update to Lumia Denim & Windows Phone 8.1 GDR1?” tutorial.
Lumia Denim update brings goodies from both Windows Phone 8.1 update 1 and Lumia Denim Firmware update in one. Read all about Lumia Denim and Windows Phone 8.1 GDR1 changes at our dedicated page.
Thanks Adv32 for the tip. Cheers!!