In an infant car seat, the first thing that you should do is install the car seat base to the seat. The base of the car seat is installed separately to make it easier to get the car seat in and out of the vehicle.
To install the car seat base, set the base in the middle seat of the car as shown. The base of the car seat should sit at a 30-45 degree angle when it is sitting on the seat properly. Use the car seat's angle indicator if available.
Use the vehicle's seatbelt to secure the car seat base to the vehicle. All car seats have a "path" to thread the seatbelt through.
Lock the seatbelt. This is achieved by pulling the seatbelt all the way out. Once it's all the way out, allow it to retract back. You will hear it retract while it's retracting.
Tighten the seatbelt by placing one hand on the car seat base and holding the seat belt shoulder strap with the other hand. Simultaneously pull the seatbelt slack while pushing down on the base. This will secure the car seat base very tight so that the base doesn't move out of place.
Check the base for slack. The base should not move when wiggled more than an inch at the seat belt path. Double check the angle.
The most crucial step in this process is to make sure that the car seat base is tight when buckled and does not move more than an inch.
Lastly, install the car seat in to the base using the "click connect" system. Do this by setting the car seat on top of the base, with the car seat rear-facing.
**Tips for Frequent Users:
1. Dress the infant in tight fitting clothing. During the winter months, make sure the infant is not wearing any bulky clothing, but place a warm jacket next to the car seat for when you are taking the child in and out of the vehicle. Bulky clothing can cause improper strap placement of the car seat.
2. The shoulder straps inside the car seat should be a the lowest position possible (depending on how big/small the infant is) and the chest clip should be at armpit level.