I'm very sorry for your loss. And it is very thoughtful of you to think about preserving your husbands memory in this way, for your children.
I am wondering if it might be easier on you to put your husbands shirts away for the time being, because I would think your loss is too fresh. It might be helpful for you, after watching some videos, to go to a thrift store, buy maybe 4 or 5 shirts and do some practice. These won't have any emotional attachment for you. You could make a throw or child's quilt to donate. The questions you have, and the mistakes you make will get worked out before you cut into your husband's shirts.