Gather these parts
Glue the side plates onto the back as shown
Glue the top plate on as shown
Glue rim to the bottom side of the platform
NOTE: There are two other basic platform variants in the Odinheim line. Each of those assembles in the exact same way and just has a different shaped top plate and rim.
Prime with Rust-o-leum Profesional Enamel flat black and paint as normal with hobby paints.