Graphic design

I am launching a new online buisbess which has a franchise element to it therefore I need a logo and header and profile graphics for facebook and twitter to give the multiple users (franchisees for lack of a better word) of my business a brand unity on their own social media. It is a local food/ food hubs/ online farmers market business...see The Food Assembly and their graphics (theirs is a bit too colourful but I like the simplicity of it). They are the platform I currently use but they are withdrawing from the UK.