How to set Huawei's mobile phone SMS avatar?

You open the SMS interface, then hold down your black and white avatar for a long time and let go of your hand "Click here to edit contacts". After clicking, you will see a box with a camera in the upper left corner, and then click three options to select photos. After selecting photos, you can save them. I just bought Xiao 7, which just came out last week, hahaha.