Hi Lee. My name is Cindy. You could hang lights around the top of your cubicle and then drape garland right below the lights. I really like all white Christmas lights. but use your choice. You could use red construction paper to make a chimney. Just draw bricks on it and put a white top on it. You could also make it look like there's a fire in the fire place. Hang stockings across the top. It's really nice that your employer lets you decorate for Christmas. Have fun doing it. p.s. Dollar Tree sells construction paper.
Hi Lee, here are a few ideas that might inspire you - https://www.blurmark.com/office-christmas-decoration/
Pinterest has some ideas for you:
Could you hang garland and lights? Thumbtack ornaments to the wall in the shape of a tree?