Use the following website to bridge Arbitrum Goerli to Xai Testnet: https://bridge.arbitrum.io/?l2ChainId=47279324479
Be sure to select Arbitrum Goerli in your wallet and then confirm it says "Arbitrum Goerli" in the top right corner of the website.
If you simply connect to Goerli, or Arbitrum Goerli, the bridge page will automatically switch to the correct testnet view. You'll then be able to see all the corresponding networks in the dropdown, including Xai.
If you are connected to mainnet, and do not switch networks manually in your wallet, you can enable testnet mode in the bridge by clicking on your address in the top right --> clicking "settings" --> and then "turn on testnet mode". Then Xai will appear in both the network drop down in the top navigation, and as an option in the bridging interface directly.
Enter the amount of testnet ETH to bridge from Aribtrum Goerli to Xai Testnet
It may take a few seconds for the transaction to complete
This is what you should see when the transaction completes.