Flippr for Flickr uses a "sliding drawer" main menu (same as Gmail, Google+ or Yahoo Mail). To show the main menu, tap on the left side of the title bar (see the 3-line icon in the adjacent image).
Practically every view in Flippr for Flickr has an actionbar at the top. Depending on the device and the available space, some of the options are grouped in the "overflow menu". To show the overflow menu, you have to tap on the "three-dots" button in the top right.