First upload the picture you need to the album in Baidu space. When you want to set the signature file, click on the picture in your own album, copy the URL of the picture, and then go back to set the signature file. The window needs You fill in the name of the album you are in, and then you enter the copied URL, and the pictures in your space will appear. That's good. Wait for it to verify the pictures and set your signature file.
Note, it is a Baidu space photo album. It’s not a new Baidu photo album