I can't believe I am willing to show pictures of the tops of my cupboards.
Make sure you have rubber gloves to wear while you use this, the borax can be hard on the skin, and you want your water hot.
Grab a cloth, a rag that you aren't worried about staining, a sponge, or something, and start cleaning.
I also used this to clean my range-hood filter and it worked like a dream. After removing it from the hood, I soaked it in the grease cleaner right in my sink.