Events are easy to add in REDCap. Just go to Project Setup, make sure "Use longitudinal data collection with defined events?" is enabled, and then select Define My Events.
This will open the Define My Events screen.
If you need to add events, you can fill in the details and add events one by one to your project.
Or you can select Upload or download arms / events
Download your events file and make additions and or changes, then save the file as CSV.
Select upload file and upload your saved file. This will add new events to REDCap.