Gather these parts

Peel off the protective paper and superglue the acrylic detail sheet to the back of the MDF window sheet

Gather these parts

Slot the sides into the front and back panel

Glue the base onto the bottom

Gather these parts

Glue the strips into the slots 

Slide the sheet from the previous step into the wall from the previous steps.  You may need to flex the upper bar out to get it to slip in.

The strips with the slots on the bottom will hook over the base 

Gather all these parts

Glue them all into the slots on the back of the window as shown above

Gather these parts

Glue the gathered strops into the front of the window assembly

Gather the window frames

Glue the window frames on as shown

Glue the ring onto the round window frame

Glue the top ledge onto back frame

Glue the top on to the wall so that the wide slot is over the gap adjacent to the acrylic details sheet

This is where you can insert the acrylic after painting is complete.  Use glass froster spraypaint if you would prefer a matte finish window.

The top can be left un-glued so that the acrylic can be removed if desired