Sigma provides a straightforward way to add your company logo to your reports. You can make this a default setting in your reports, and the logo will be shown in the upper right-hand corner of all reports.
Click on the Reports tab in the tool bar, then click on Settings. In the Edit report settings dialogue box, click on the Logo tab and browse to the logo file you want to use. (*.jpg and *.pdf are the default file types but *.png also works.) After selecting the logo file, click on OK.