To the other excellent answers, I would also add that many new mothers experience a lack of confidence, and sometimes this is made worse by the fact that they had to have a C-section (it is a bit irrational, but it can feel like you somehow failed at your first basic task of motherhood). As you have taken over much of the care, it may have made her feel more inept, especially as you have corrected her way of holding the baby and perhaps have given her other tips, thinking you were encouraging her involvement.
I would suggest you step back. Trust her to take care of the baby and give her a chance to rise to the challenge, to find her own way to hold and diaper and soothe baby. Show confidence in her, but avoid adjective-laden praise as it makes the work of caring for the baby something you need to approve of. Instead, you might comment on things she does well in a more neutral way:
You got her to sleep in less than an hour - it took me a lot longer than that.
I think I was making her nappy too tight - she looks more comfortable the way you do it.
I am so glad you are feeling a bit better from the surgery. I know you are not 100%, and you are managing amazingly well. I didn't even have surgery, and I was exhausted!
You will need to let her do things her own way even though she will do things differently than you and perhaps initially not as well as you. She needs to grow into this role by trying things and making her own successes.
Many new mums get a slow start, but with experience I am sure your wife will be great.