how do you change coolant in peugeot 206 how much water does it hold

er, you dont ''change it'' you merely top it up, or add antifreeze.

and that happens in the header bottle.

and DONT open the cap when its hot, youll get scalded.

You are best to leave it to a proffessional. It is not as simple as just swaping it. You are best to just keep it topped, if lou get an air lock you could over heat the engine and cause major damage.
Charlie

thiers a release valve/knob on lower side of radiator. when engine is cold, open/remove engine coollant reserve cover, then open the radiator knob, when coollant as drained off, close the knob, re-fill coollant reservoir and replace cover and run engine for about 10 mins, wait for engine to cool and top-up the reservoir. you will need about 2lits of coollant, you will top-up with tap water, cheers.