IF you poured it into the expansion bottle and IF you have not run the engine, take the expansion bottle out and wash it out*.
You should also drain the radiator and engine water and flush it with fresh, a couple of times, before refilling with antifreeze mixture.
If you have run the engine, flush it a few extra times, then, when you think it is clean, run the engine to normal temp with clean water, allow to cool, then drain. repeat once more, then refill with antifreeze mixture.
Do not run the engine before you have emptied and washed it out. This will minimise risk of damage to e.g. seals and the pump.
* If you cant see how to take the bottle out, remove the pipe that comes from the radiator, and put the garden hose in there to wash the bottle out. use plenty of water as the brake fluid will strip off paint, so using the hose will ensure it is quickly washed away with plenty of clean water. Hose away any spillage.
