To change your branding and images click visp then branding.
You can download the default css stylesheet please do not rename the stylesheet otherwise it will not work.
You can also view and upload new images for your logo and products. Images need to be in a gif or jpeg format. When you then edit the product you can choose which image you wish to show.
To edit images place a tick in the box view images. To change an image you just need to make sure that the image you want to replace is called the same name as the image already there.
You can save a copy of the image by right clicking the image and select save and then you can edit the image with an image editor e.g. Photoshop, then upload the images using the image upload tool.