A new client record is created in two ways:
1) Automatically when a new booking is made by either you or the client
2) Manually via the Clients section in the menu
When a new client makes a booking with you then a new patient record is automatically created for you pre-populated with all of the information provided by the customer at the time of the booking (this can include any answers to any templates you have automatically sent out). This includes personal details and information regarding the injury.
If you are adding an appointment in to your calendar then if the name entered is not an existing patient it will give you the option to create a record for them.
Likewise, if a client exists, you can find them by clicking Clients in the menu, searching via the search box for the client, then selecting More next to their name, and finally View Notes. You can then add a new note by selecting Add Note.
If you have external patient records then these can be simply imported via CSV file as explained here.
Information on how to view, add and edit patient notes can be seen here.