Follow those steps:

• Give the Gallery module a Title
• Enter You Flickr API Key. If you don’t know how do get my own Flickr API Key? Then make sure you are already logged into your Flickr account before going to click on that link: https://www.flickr.com/services/api/misc.api_keys.html ....and there is also second way, use this online tool: http://idgettr.com/
• Enter You Flickr Album ID. If you don’t know how do get my own Flickr Album ID?  After login Flickr will redirect you to Home Photostream Page, select the Albums menu link to go you photo album page. Check the Browser URL to get your Album ID. Those are only numbers in last section of url, without "/" etc.
• Choose a module position.
• Assign into selected menu items.
• Choose Publish option and then Save button to prepare your Flickr album.