All I did was basically mount a long shelf. I had a 1 x 12 cut to size (around 50") and stained it in a dark ebony color to match the other furnishings. Then I used 3 Ikea Shelf Brackets at $2.00 each.
I then added a couple of Ikea Rails. This allowed me to attach a basket to put pencil cup holders in.
I used laundry twine from the Dollar Tree and nailed 3 rows on top of the desk for the kids to hang their finished art projects. Some Clothes Pins to secure their art and it was a wrap.
Super easy and fun project and the kids love it!! If you need stools there are always the ones Target and Walmart sell for around $12.00 each, or you could also mount the desk at chair height.