To do this, access https://app.checkinscan.com/client/login with your username and password.
Once logged in, go to the Reservation section and click Add Reservation:
There, you will need to fill in the property, check-in and check-out dates, and the number of guests staying. Optionally, you can also complete their contact information (name, phone, email). The description and any other information you enter will only be visible in your account and will not be shown to the guest.
To finish the process, click the "Create" button, and you will be able to view the booking in your bookings list.
Keep in mind that if you enter your guests’ email addresses in the bookings, you can enable automatic sending of instructions for completing the online check-in via email.
If you want to import bookings generated on your booking platform through an iCal link, here are some articles to help you with the setup: