Well, perhaps it's safe to say that every site needs a logo and here you find out where to go to upload yours. Here are two quick tips to help you on your way.
TOP TIPS:
Size your image dimensions before uploading. If your logo is positioned to the top left, consider a rectangle around 400x100px (no wider). We'll do the rest to make it work on all devices.
Remove any background colours from your logo image (e.g. white background). You can do this by saving the image as a png with a transparent background.