The update, which automatically transforms the main Personal Paint 7.0 or 7.1 program file to version 7.1b, can be downloaded from Aminet, biz/cloan directory:
http://ftp.uni-paderborn.de/aminet/dirs/aminet/biz/cloan/PPaint7_Update.lha
For additional information please refer to the text included with the update, and to the Personal Paint FAQ at:
http://www.cloanto.com/amiga/classic/faq.html#PPaint