Specs

Email graphics (build within concierge.com or upload html) - recommended width is 600 pixels

Banner image (1140px x 287px - .jpeg, .png, .gif, .pdf) for Registration page and Itinerary

Color palate - there are multiple places to customize the colors, such as Registration and Itineraries, so knowing Hex codes, Pantone or RGB codes for your brand's colors will be helpful.