You can add your company logo to the payslips by going to the Pays screen, clicking the Payslips button and selecting 'Configure Payslip Logo'.
Tick the box to turn Logos on and then select 'browse' to choose the image. You can adjust the height or width of the image by adjusting the measurements in the logo menu.
The preview will show you how the logo will look on the payslip. Once you are happy with how the logo will appear, click 'Close'.