Go to 我(Me) > 支付 (Wallet) > 收付款 (Quick Pay) > scroll down to ‘向银行卡或手机号转账’ (Transfer money to bank card or cell number) > choose ”向银行卡转账’ (Transfer money to bank card)
Fill in receiver’s name (姓名) exactly as it appears on their bank account, card number (卡号), and bank (银行, you choose from the list). Once you fill it in once, the details will automatically fill in once you start typing the next time.
That’s it. It’ll tell you that the money will arrive in the account within two hours, but in my experience it’s much quicker than that – a few minutes in my experience.