Don't lose your cool
If your engine is overheating, it can be one of a number of reasons. Don’t try to solve the problem right away; first thing to do is pull over to the side of the road. Switch the engine off, open the hood and leave it open.
Turn your air-con to full heating and turn the blower on. This will draw some heat away from the engine.
If there is steam billowing from your engine, wait for it to clear then inspect the coolant level. It is the reservoir with the green/pink fluid in it.
Billowing steam is also an indicator of a leak in the system, in which case it is probably be a good idea to keep the engine switched off.
This is a worse problem than it appears because no engine means no power steering and no brake servo either, so steering and braking while being towed will take Herculean strength.
If your coolant level is low, then top it up. Do not open the reservoir until the engine has cooled down. Wait at least a half hour before you try this. This is very important because the coolant in the system is sealed, so opening it while the engine is hot will only result in superheated steam escaping and broiling you like a lobster in a pot on the stove.
Water might work in a pinch if you can’t find coolant but it isn’t advisable. Today’s coolants are carefully prepared mixtures of distilled water and ethylene glycol.
If you have no choice but to drive on, let the engine cool, then drive slowly, shifting up at every opportunity. Keep an eye on the temperature gauge.
Cars like the VW Polo don’t have a gauge, they just have a warning light when the engine is too hot.
This will give you less warning, so be more careful if your car doesn’t have a temperature gauge and just a warning light.
If you have a leak, you will need the help of a mechanic to fix it. Fixing it yourself is far too complicated for a DIY.
Above all, don’t try to push your overheated engine too much; an engine rebuild costs more than you expect.