What a certified copy is
The notary compares a photocopy against the physical original in front of them and certifies, with signature and seal, that the copy is a true and complete reproduction. It is not a sworn statement.
What to bring
Bring the genuine physical original — not a scan or another photocopy — plus valid photo ID. For a multi-page document, typically the first page carries the seal and the rest are endorsed.
If you only have a scan
If no physical original exists, a certified true copy usually isn’t possible; a statutory declaration about the document may be an alternative. Check what the receiving institution accepts.