There are multiple ways to input a Reference Image for img2img and Composition Control generations
You can drag and drop any output images directly into the Reference Image box to quickly create new iterations
You can paste an image from your clipboard by using the keyboard shortcut
PC : hold ctrl and press V
MAC: hold cmd and press V
You can load a Reference Image from the Image View screen by clicking on the Edit tab and clicking Refine
click on import inside the Reference Image box to upload a Reference Image from your local hard disk