How can I darken the color of the pressed wood on my computer desk?

minwax makes polyshades...stain and poly in one ...not fast drying tho....put the cat in the pet box overnight...

Pressed wood (MDF or particle board) should not be the surface material. Most likely it has a thin layer of vinyl. (like shelf paper). It is not worth the cost of the finish you will need to buy, but if you must, a spray on paint for plastic would work the best.

If you look around at your local hardware store, you will likely find furniture scratch repair markers. They look, and work, just like regular makers. They usually come in light, medium, or dark.

try dark stain on it

sounds like you will have to paint