You can easily upload your logo using your corporate admin dashboard.
Login to your account and follow these steps:
- Click on Profile form your admin menu
- Click on 'Upload logo'.The size for the logo is 200kb and there is no specific dimension for this accept it need to be square.
- Click on 'Upload Banner'.The width of your banner must be: 1500 x 450
- Scroll bottom of the page and click 'Update' to save your logo&banner.