If you want to input your leads manually, you first need to create an empty list. Go to Manage => Lists => Add a new list , click on "Empty list" and type in a name for your list and hit "Next".
Once you have your list, you'll need to define some fields to it in order to be able to add leads. But that is all explained in the next section of this guide: Tweaking Your List.
Where does your data come from?
If you have data coming in from other online systems, check out our guide on integrations for inspiration.
Create a completely empty list and configure it to upload leads manually.