Opening Zotero
On your computer
Once installed, open Zotero by clicking on the software icon. 
Since you have not yet collected any references, the interface will be relatively "empty". You will explore the interface in detail in Chapter 2.
In the browser
Another important thing to check once the software and the browser connector are installed is the presence of a small Zotero icon in the top right corner of your browser.
Below is the Zotero Z icon as it appears when launching Firefox:

Depending on the browser, the icon may look different and you may not see a "Z" but rather a folder icon corresponding to the type of page or document displayed: 