There are plenty of websites out there where you can find free pics for your graphic design use. However, be sure to fully read the licensing terms before using the free stock pics, even though they claim to be free. Some websites that offer free stock pics include Gratisography, Unsplash, Life of Pix, Death to Stock Photos & PicjumboBlackEncryption
CMYK (cyan, magenta, yellow, black) is a four-color process model, which is used for color printing. RGB (red, green, blue) is a color model that is used for displaying images on electronic systems, including computers and televisions. When implementing graphic design for print, all images and assets must be converted to CMYK color in order to print properly. This is done in Adobe Photoshop or Adobe Illustrator. When images are converted into CMYK color, they may not be as vivid and vibrant as they were displayed on the screen.