You have to register for three months to use the signature map of Baidu Post Bar.
When the time comes, you upload the picture to your Baidu photo album, then extract the link of the picture and set the signature map in the personal settings of the personal post bar.
Remember that the maximum size of a signed picture is 500*200, and it will be compressed if it exceeds it.
You can set up up to 5 signature graphs. You can choose which signature map to display when posting, or you can choose to display it randomly.