How to get kids in the car

This might sound silly.. but how do I get my 18 month old and 6 week old in the car by myself?? I had a csection so I’m still feeling weak. I just started lifting my 18 month old (she’s heavy.) how do I safely get them both into the car from the house. And carry stuff. Just make trips?? I know it sounds ridiculous but I haven’t done it yet by myself lol I’m just nervous clearly!

For reference my 18 month old is behaving terribly lately, doesn’t understand hand holding yet and I get nervous bc we live on a main road.