Finishing You may finish your desk any way you like. You can simply paint the desk if plan to use it only for a short time or you can do a little better job on the finishing. Plywood edges take some effort to seal. The end result should be uniform in texture and not have holes one place and excess filler another. First fill all visible holes with glue and wood splinters.
Toothpicks work well.
Let dry and sand with course paper over a wooden block. Let this dry thoroughly and sand again. Seal with a thinned coat of shellac. Sand again and refill. Sand again, seal again, and sand with fine sand paper.