Are you able to print the label yourself at home OP?
If you have a printer, open the Evri label in the message. They give you the option to either print at home, or print in store, then you just need to drop it off at your local drop off and they will give you a little blue ticket to keep as your proof.
Please don't feel bad. I was overwhelmed once, as I had no printer and tried to use the one in the library, but it was too complicated and I left, without a label, almost in tears of frustration. Thankfully you now have the option to always print in store, which has made it so much easier if you don't have a printer.
If you don't have a printer, choose print in store. You will be emailed a label. It will contain a QR code. Once in store there is a dedicated Evri printer. You press begin. It asks if you have a code. Press yes, then show your QR code to the screen. It will print automatically. Sometimes it can take bit of jiggling before it picks up the code.
Just check before you go that your local Evri has the facility to print in store. If it doesn't you need to go to another one that does. Check on the store locator and it will tell you which ones print in store.
Good luck!