If you are just getting started, it is very useful to at least enter a swimmer's best times for each event:
On the swimmers Times tab you can manually enter any time.
On the same page you can also upload a CSV of swim times for adding times in bulk.
You can use sites like SwimCloud or SwimStandards to find times tables that you can copy and paste into a spreadsheet, then export as a CSV. These sites will have a current list of best times for every event. If you want to spend the time, you can go event by event and add ALL swimmers times to the spreadsheet.
What are the various swim time tools?
What is a swim season and how do you plan it?