Our concept- run your website/application in your brand name so, have your logo in the site/app for a better brand recognition. Follow the below steps to upload your logo.
In Settings--> App Settings--> App Logo section click on the image field and select your logo file from your system. Size of the logo should be 200X150. Now Save the changes made to the setting.
Now your logo has been uploaded and can be seen in left side of your header tab in all pages. Your website now is in your brand.
Favicon is the website/tab icon of your web page seen in the tab menu. Go to Settings--> App Setting--> Favicon and select your Favicon image in ioc format of 20X20 size from your system and upload in the Favicon field. Click Save to save the changes.