How to change a flat tire

Read this once now, so you're not reading it for the first time at the side of the road.

1. Stop somewhere flat and safe, away from traffic. Hazard lights on, handbrake on.
2. Get the spare, the jack and the wheel wrench (usually under the boot floor).
3. Loosen the nuts before lifting the car. Turn each one about half a turn counter-clockwise while the wheel is still on the ground.
4. Put the jack under the car's jacking point (check the manual; it's a reinforced spot near the wheel) and lift until the tire is just off the ground.
5. Take the nuts off, pull the wheel off, and put the spare on.
6. Screw the nuts on by hand, then tighten them a little in a star pattern (across from each other, not around in a circle).
7. Lower the car, then tighten the nuts fully, again in a star pattern.

Small "space saver" spares are only for short distances at low speed, usually under 80 km/h. Get the real tire fixed soon. Check the spare's pressure a couple of times a year so it's ready when you need it.