You can erase blocks with editor id 2- left click on the mouse to do so. Use left and right arrow keys to change blocks to build with. Click on the "generate new world" button to generate a world with your preferences. Height noise is the difference in height between blocks. Biome 1 is forest, 2 is plains, 3 is snowy, 4 is swamp, 5 is ocean, 6 is desert. Click the "g" key when done to generate your new world. You will get a random world when you first start.
Currently in version 2.5, more updates soon. Next version: 2.6 new stuff to come: nether dimension birch forest commands extreme hills time/clock for time played