Bottom left hand corner of you REW graph is a floppy icon.
Click it to save a jpg of the graph that is 800 bits wide suitable for posting.
For subwoofer plots, always use the standard Vertical graph axis of (45dB - 105dB) and the Horizontal graph axis of (15Hz - 200Hz) using the Graph Limits button in the top right corner of REW. Use a measurement start frequency of 0Hz and an end frequency of 200Hz. Use the appropriate target line that matches your crossover.
You require five posts before you can show jpgs, so go the post padding thread to create some dummy posts.