You will need to verify your account and make a deposit via the method you want to withdraw to. You will also need to playthrough the amount you deposit first as well.
Verification involves sending them copies of documents - ID and Address Verification (Something like a utility bill). It take a while to complete too a week or two.
Credit Card is a little tricky some countries it is available as a method of withdrawal other regions like mines you can only deposit with Card. There is also a $100 minimum withdrawal amount as well.
If you deposited via Credit Card when time to withdraw to it they may ask you for a copy of the card with some of the numbers blacked out. Not 100% sure as I never withdrew with card from 888 but I had to do it on all other sites I withdrew via card.
I use
neteller for all of my banking transactions on 888.
You can ask the 888 representative found in this thread they will be able to better assist you.
https://www.cardschat.com/forum/poker-rooms-10/888-poker-official-support-thread-252119/
if i make a my first deposit on 888 poker does this allow me to collect past winnings before i made my first deposit?