A different car seat question

AshleyS26

I recently got a convertible car seat and was very excited to start using it, I read through the owner's manual and now know that I have to wait a bit longer because LO has to be at least 20lbs (she is 15lbs 10oz right now). As I was reading the manual I could not find instructions on how to hook it into the car rear facing; I know that it is recommended rear facing until age 2, and was planning on sticking to that guideline. In the store on the tag it said rear facing and forward facing, but no where in the instructions does it tell how to latch into the car rear facing. I was planing on taking it back to the store, but DH threw out the box. So WWYD?