K.:
Hello and good morning! First of all - thank you to your husband for his service and sacrifices to our country - much appreciated!
Installing a car seat for the first time can be daunting. If you call the non-emergency number and ask if your local police or fire station does the car seat check.
Depending on the car you have - do you have one that is permanent or removable? Permanent is really good - just tough for the first six months because you can't take the car seat with you when you get out of the car. Permanent, Use your knee and lean/press (it's okay to use your full weight!) the seat into the vehicle seat/bench. Pull the belt through and lock it in place. Pull the belt tight and ensure it locks. The car seat should NOT move - tilt, etc.
If you have the removable car seat - just install the base (just like above). Again it should NOT move in any way.
Oh yeah - you can contact your local Babies R Us and find out when their next car seat safety check is. If they don't have one in the next week or two, ask them where you can go as well. Sheriff's departments will know as well.
CONGRATULATIONS!
Good luck! May you have many happy memories!
Cheryl