First of all, you should activate them for your project. Project settings -> Modules, check Deals and click save.
How to add deal statuses
Go to Administration -> Contacts, Deal statuses tab. Here you can add new statuses, modify or even delete existing ones. In order to modify an existing status just click on its name. You can change name, color, status and decide if it should be a default status.
Newly added statuses are not visible by default. You need to activate them for the particular project(s). To do so, go to Administration -> Projects -> Select the projects -> go to Deals tab, and then activate the statuses you want to use in the certain project(s).
How to create a new deal, how to import and export deals
There is an article about it.
Go to Administration -> Roles and permission and edit permissions if you want to enable certain roles to manage and view deals. There is an article about it.
Please note that everything connected with deals is PRO feature only.