If you think you might consider changing a wheel in an emergency, then you could practise at home in the daylight when the weather's warm and dry. Then, if you do suffer a puncture you'll be able to cope more easily. even if it's dark, cold or wet.
Plan the job so that the vehicle is raised for the minimum amount of time. Switch off the engine and tum on the hazard lights. Apply the handbrake and engage first gear (or 'P' if an automatic). Chock the road wheel diagonally opposite the one to be replaced. Remove the spare from the boot/carrier - take care as a carrier under the vehicle may be rusty and difficult to move. Lay the spare on the ground where it will be convenient for fitting - make sure it can't roll away. Remove the wheel trim (if fitted) - you may have to cut cable ties and/or lever the trim off.
Place the jack in the recommended lifting point closest to the wheel to be removed. Ensure that the jack head engages correctly (as shown in the handbook) and extend the jack until it just starts to lift the car on its springs. Don't lift the car any further yet.
Slacken off the wheel nutsfbolts (most turn anti--clockwise to undo) using the vehicle's wheel brace and, whcre appropriate, the locking wheel-nut adapter. (There might be a protective cover over locking wheel nuts - prise it off if necessary.)
Keep your back straight and body weight evenly distributed on both feet. Apply effort downward and in a controlled way so that when the nut finally 'breaks' you won't lose your balance or fall over. It is possible to achieve greater efficiency by applying controlled effort through the foot, but only if you can support your upper body.
Raise the jack to lift the vehicle suffiently so that the wheel is just clear of the ground. Remove the slackened wheel nuts/bolts while keeping the wheel in position on the stub using a knee or toe - leave the top one until last so that both hands are free to lift the wheel away from the hub. Fitting the spare is the reverse of this procedure - ie secure the wheel by making the top bolt/nut the first to be replaced. All the nuts should be finger tightened in stages and in a diagonal sequence. Don't oil the bolts/nuts before refitting them, as this will make them more likely to work lose. Carefully lower the wheel to make contact with the ground before fully tightening the wheel nuts - again in diagonal sequence. Stow the damaged wheel safety. Replace it in the carrier or boot well.
If the spare is a temporary-use 'skinny' spare, then note any restrictions on use - they're typically limited to 50mph and should be replaced with a nonnal tyre as soon as possible.
Some dashboard lights may come on while a space saver spare is used because systems like ABS, traction control and some automatic gearboxes can be upset by odd tyre sizes.
Check/adjust the pressure in the 'new' tyre as soon as possible. Get the wheel nuts tightened to the correct torque figure as soon as possible. Get the damaged tyre replaced or repaired as soon as possible.