Start by navigating to the Contacts section from the navigation bar on the left.
Here you can see all your contact lists with customers and empoyees alike (switch between the two by clicking the tabs near the top).
Click on the list to open it and view the contacts included in it. In the list view you can also search for a particular contact using the search box or filter contacts by their status with the Status drop down menu.
If you need a new list, that can be created with the Create new list button in the upper right on the Contacts page. You can find a more thorough explanation of this in the Contact lists article.