Almost every casino asks for ID when you want to sign up or cash your winnings. In most cases, a driver's license won't do. You will need to present a passport or identity card. Furthermore, you need to produce formal adress documents, like a bank account statement which links you to your adress. You can hide your financial data or other sensitive but irrelevant information on these documents, like your social security number or balance amount.
How to transfer your data to the casino
You can scan your passport, ID card and other documents. Most casinos offer the possibility to email or sometimes upload ID papers. Make sure you only upload private documents through safe websites (check the adress: the URL should start with https:// and show a tiny lock left of the URL). If you have difficulty with scans or email, you can ask for a possibility to send the documents through normal mail.