Measure the available wall space and buy a corresponding sized piece of netting. Waxed shrimping nets are ideal for this.
Pull lengths of jute thread through the net mesh. Jute thread is a matted mass of threads available in a range of camouflage colors. Alternatively, use strips of appropriate-colored cotton.
Attach the colored strips to the net using basic needle and thread. Spray glue adhesive can also be used.
Put up hooks along the top of the wall where the net is to be hung and attach the net by looping the mesh onto the hooks. Picture hooks, nails or cable retainers are all suitable for this.