This page "Enter Payments" provides you a list of tenants so that you can choose the tenant whose payment you would like to submit.

You can also search for a specific tenant by entering that tenant's name in the search field and clicking Search

After clicking Search, the tenant's name will appear.
Against the tenant's name, click the button "Enter Payment".
This will take you to a form where you can Enter and submit the tenant's payment for a specific month or period of time