How to send an important document to an institution via USPS overnight express mail service?

I need to mail out a really important document to an institution via USPS overnight express mail service.

But, this is my first time to use this service. So I want to know how to use this service correctly.

I will appreciate it if you give me an instruction step by step to use this service. for instance, what kind of envelop I have to get, Do I need stamps or not, how can I get my tracking number, etc.

Thank you !!!How to send an important document to an institution via USPS overnight express mail service?
You will have to go to the Post Office.

Ask them for an Express Mail Envelope, and an Express Mail Shipping Label.

Complete the Shipping Label and

stick it on the Envelope. Insert your

document in the envelope and seal it.

Go back to the Post Office and hand it in over the counter and pay the Postage. The Post Office will give you a copy of the Shipping Label which shows the Tracking Number.