Take care to prevent the car from rolling backwards. If it rolls off the jack or stands, it may cause serious damage to the car or you.

Park the car on a flat and level surface.

Block wheels. Make sure that your chocks are tight against the tires. Give them a few kicks to ensure this.

Engage emergency brake.

If you do not feel comfortable, take your car to a shop. This is an easy job for a professional and they won't charge too much.