When you add your property, you should add/edit all settings in order to set it up. To access property settings click on your property name (top right) and select Property settings.
There are 4 categories and 5 tabs under general property settings. Each tab represents one set of settings you need to complete in order to use Rentlio effectively. The first step is to enter basic information about your property: property name, address, contact details. When you're done be sure to save the changes before opening a new tab. In case that you want to delete the property at some point, there is Delete property button on this screen as well.
Initial set-up decribed here.