ebrake light keeps coming on

The Brake light is tripped either by the E-brake or the low fluid sensor.

When it goes on and off it's the fluid sloshing around in the reseviour intermittently tripping the sensor.

With that said, NEVER add fluid.

You either have a leak and need to find and fix it,

Or most likely your brakes pads are low and you need to replace your pads. The reason you don't want to add is because when you push the pistons in, the extra fluid will spill out of the MC and all over your engine and engine bay. Brake fluid eats paint, so you definitely don't want that to be splashing around.