Create a Material with your custom JPG as the Texture -- scale the Texture to the size of the wall -- assign this material to the face of your wall -- you may have to adjust the origin of the Texture, in which case from within the 3D window, goto Design > Align 3D Texture > Set Origin, and click one of the bottom nodes of your wall.
MacBook Pro Apple M2 Max, 96 GB of RAM
AC27 US (5003) on Mac OS Ventura 13.6.2
Started on AC4.0 in 91/92/93; full-time user since AC8.1 in 2004