#Crochet and #Sewing folks, I need your help.

I'm making a crochet pencil case. I'm planning to line it with some cotton fabric.

There are three separate panels (two in the images) to be sewn together. Should I line the crochet pieces before I sew them together or after?

I will be doing the work by hand as I don't have an easily accessible machine.

My sewing experience is limited to reattaching a button and making one or two wonky pouches, so assume I know next to nothing about it.