By default, the product will sit on a white background, but you can specify your preferred background color other than white.
From the customer dashboard (https://pixc.com/dashboard),
1. Upload the image you need editing
2. Click Next: Choose Template
3. On the Choose Template section, click Create New Template
4. Under Basic Options -> Background Color, click Other.
5. Input the color swatch you want to use. You can either enter the swatch, or choose from the colors available.