Getting started on xDAI
The first thing you need to do is add the network to your Metamask:
Network Name: xDai New RPC Url: https://rpc.xdaichain.com/ ChainID: 06x4 Symbol: xDai Block Explorer URL: https://blockscout.com/xdai/mainnet
Note: Chain ID 0x64 is the hexadecimal equivalent of 100, which is the xDai Chain ID. MetaMask recently updated the ChainID to be a required field. When you update, you may need to reenter the Chain ID: 100, and it will be converted to a hexadecimal: 0x64
Once you have the network set up you will need native xDAI in your wallet to transact. Treat xDAI the way you would treat ETH on Ethereum. This is what pays the gas fees for your transactions.
xDAI Faucets - Getting a little xDAI for gas to get started: