There are a few ways to authenticate documents:
1. The first way is to contact the issuing authority of the document and request an authentication letter. This letter will confirm that the document is valid and has been issued by the authority.
2. The second way is to take the document to a notary public. The notary will witness the document and sign it, confirming its authenticity.
3. The third way is to contact the embassy or consulate of the country where the document was issued. The embassy will be able to confirm the authenticity of the document.