You will be charged for the cost of the transaction plus the size of the avatar as everything will be stored in the blockchain
You need to have Metamask connected and funds in your wallet as you will be asked to sign a transaction, once the payment is confirmed your account will be created with a unique address, that's the contract of your stream
Metamask will ask you for one confirmation
Your contract address is 0x1234567890123456789012345678901234567890
Save it in a safe place as that's the only way to access your stream
Share it with your friends so they can follow your posts