You upload your files(documents, copies of your ID) on an IPFS implementation over Persona blockchain. They are encypted by the blockchain itself using your private key.
Let's suppose you want to sign up for a contract with a new mobile carrier. You have your identity checked on Persona blockchain. What the mobile carrier staff will do will issue a request to have read access to your details. They will generate a QR code that you scan with your phone and you'll see that X company is requesting access to your date birth, address and ID. You'll sign with your private key and give access to your uploaded documents on Persona blockchain to see if the person they have in front is the same with the person from the documents. And that's all.
Every companyy that has an onboarding process they have just to make sure that the person they have in front of their eyes is the same with the person of which documents they are checking.