Sewing with linen

I know how to set up and use the basic functions of my sewing machine. I can sew a straight line on muslin. BUT - I have never successfully sewn anything yet.

I want to turn this into a pillow, using cotton fabric as the backing.


(Not my stitching, I'll post pics of the finished product.)

My question is this - if I mess it up, can I remove the sewn seam and start over? Will doing this distort the linen? Any tips on the best way to remove a seam if it is necessary? (I am mostly afraid of it being crooked)

Thank you in advance for anybody who can give me some hints!

Section