This thread is hilarious. Either feigned ignorance or an extremely sheltered upbringing. Can't be too sure either way, but if soap and sponge seem foreign to you, it will blow your mind when you learn the difference between slicing, dicing and chopping an onion.
When cubing a tomato, start slicing from the top but don't slice all the way through--leave 1/2 to 3/4 an inch uncut so that it all stays together. Rotate 90 degrees and repeat, you'll have a bunch of rectangular 'fingers' of tomato all attached to the bit you didn't cut. Hold on to that bit, turn the tomato sideways, and you can slice it into neat pieces with very little fuss.