You can set up payments in the next heading. Hopefully you like PayPal since that is almost the only option. I believe that this is the only option available to new sellers. On my screen it says Disconnect. If you don’t have PayPal set up then it will say Connect and have you go through the process of connecting your PayPal account to Bricklink.
The other option is payment through Stripe. You need to make an account on Stripe.com. Both these work with Instant Checkout so buyers can pay right away. The set up is similar for Stripe as PayPal. Even though a buyer can pay through PayPal without having an account, some people just don’t like PayPal.
You were able to offer alternative payments on Bricklink like money orders or personal checks. I believe new sellers don’t have this option anymore. Taking these payments are risky since money orders can be faked and checks can bounce. I don’t offer these even though I can. I occasionally have a buyer ask if they can pay this way. If they aren’t a new user and have good feedback I will allow it.