Check log
Check an order
Paste the reference from your order confirmation. It looks like LAJ-7K2MQ-X4PB9. Every state change is written to the log, and once a parcel is with USPS the carrier scans land there too.
Dashes and capitals do not matter. Paste it however you copied it.
Lost the reference
If you ordered while signed in, every order is listed in your account. If you ordered as a guest, the reference was on the confirmation screen and in the confirmation email. Nothing else can recover it, which is the point of it working without an account.