Sorry, can't really make out your desk from these pics. Have you figured out your layout? Where will you place your desk? If you'll be working at a computer during the day, think about any screen glare and place your desk accordingly. The window is small but still, the sun can be mighty. :) Do you need storage? Seating? Whiteboards or bulletin boards? Figure out the function of the room first then concentrate on its form. What style appeals to you? What colours? Do you want the office to have a calming or energizing vibe? Have you looked through pics on Houzz or Pinterest to get decor ideas?

you need to post a picture of the desk as a whole all we are seeing is finish. my thoughts are to do floor to ceiling shelving on the wall that has the lowered ceiling. with the desk anchored on the wall under the window giving you a small view of the outdoors and the door. bring in color with a rug and art. any color you like will go since you are starting with a blank slate. having shelving behind you makes it possible to reach everything by just turning around in your chair. a view of the door and outside is nice. a larger art piece directly in front of you is also nice. a desk facing a wall is NOT an inviting place....

look into doing some built in shelving on that wall. use ikea hack w/Billy Bookcases (plenty of online tutorials) if you're on a budget

you could have something along this line. paint the back of the wall a dark color so you get some nice contrast.

find a nice rug and artwork. if your desk can sit alone, do it like this. if not,