This is the guide to find the Xiaomi id. Please follow the gif and note down your xiaomi ID, Phone number and email address. Any one of them is enough but its better to include any two of them to avoid any mistake.
Please make sure that you include the correct ID in transaction because once credit loaded can not be returned. This credit not only can be used to buy themes but also can be used to get unlimited access high quality music (320kbps) just for 5 mi credits per month. Please check Get HD Music to buy Music.
