Once you've picked a sportsbook that lists Ripple (XRP) as a deposit option, the flow is the same as any crypto deposit: open the cashier, select Ripple (XRP), and you'll get a wallet address (usually with a QR code for mobile wallets). Send the amount from your own wallet to that address, wait for the network to confirm it, and the balance lands in your account.
Two things are worth being careful about with any crypto deposit, Ripple (XRP) included. First, double-check you're sending the right asset to the right network — sending funds meant for one chain to an address on a different one can mean losing them outright. Second, crypto transactions don't have a "cancel" button once sent. Paste addresses rather than typing them, and check the first and last few characters match before you confirm.