Before you can create entries, you have to enter a meet (may as well do them all at once).
Click Meets, then click the Add a new meet button at the far left of the toolbar (or click Add on the menu).
Set the course type to the proper course (S – short course meters, or Y – short course yards).
Set the meet type to AG (age group).
Set the fees if you want a preview of the cost – I don’t know what the fees are this year.
Do this for each meet.