Fill that forum and You have to upload your Valid government-issued ID like a Passport or Driver’s license etc and When your uploading finishes, finally click ‘Send’ button.
Any 1 Proof will be enough in the list of below examples,
Examples:
Green card, residence permit or immigration papers
Birth certificate
Personal or vehicle insurance card
Marriage certificate
Official name change paperwork
Voter ID card
Nondriver’s government ID (ex. disability, SNAP or national ID card)
Some other examples were listed here – What types of ID does FB accepts?
So if your submission was done in a correct way, facebook staff will give back your account within a few time of 5 or 6 days.