You can view contacts according to the company under which it falls. The Company under which it belongs is determined from the info entered in the Company Name field on the Add contact screen.
Steps to access companies list:
Click on Companies to open the screen where all the contacts are displayed according to the company under which it falls.
The screen is displayed below,
Click on any company name present under the left-bar to view the contacts associated with that company on the right-hand side of the screen.