Lync for Office 365 is a desktop application. After you install Lync, open it from your computer like any other application.
Do one of the following:
In Windows 8, go to the Start screen, and then click Lync 2013.
In Windows 7, click Start > All Programs > Microsoft Lync > Lync 2013.
If it’s your first time signing in, type your password, and then click Sign in.