Drop Circles (was Circles) has no direct user interface; you adjust settings and more through the menu-bar icon, which you can find at the top, close to your clock. By default, Drop Circles will activate on the left side of your screen when you touch the centered 60% of your screen edge. By default you see only the activation point that slides out, click on it to access your Circles. Drop Circles provides 8 customizable Circles: 4 are the first set, and the other 4, the alternative set. You have 4 utility Circles as well.
Once Circles has expanded, you can either toggle between the default and alternative sets with the Tab key, or you can enable Scroll Wheel from the app settings to toggle between default, alternative, and utilities. Optionally you can access each set directly with the modifier keys: the Control key for default, the Option/Alt key for alternative, or the Command key for utilities. In the Center of the expanded Circles, you can find the drop area for files, images, text, and whatever you can drag-and-drop. Drop Circles work on all workspaces as well as in full-screen apps. It also provides also the following utility Circles: image info (metadata and location), image resize, FTP upload, ShareIt, and translator.