Click and hold anywhere on the screen. The position of your click will be the position of the planet, the length of time of the click will be the size of the planet.
Make a second click, the distance of the click from the object will corespond to the force applied
All settings can be changed using the selectors bellow, they can massivly change how the simulation looks and runs.
my recomendation would be to make lots of small objects and a couple big objects. if your simulation gets out of hand you can refresh the page and this will reset the simulation. I also would not recomend setting the simulation values too high unless you wish to cause chaos.
hold (i) to increase the scale hold (o) to decrese the scale. To navigate use the arrow keys or "wasd".