Help needed with constructing a dress

[katara]

I've taken a top from a charity shop and I have altered it. This is what it currently looks like.
*It's loose-fitting on the dress form because my dress form doesn't accomodate my measurements*


Front:



Back:



This is what I'm aiming for but I'm not sure how to proceed. I want to make a one-piece dress. The one side seam is open (I want to add a zip) and obviously the skirt part will be full around:



I'm not sure how to proceed??  Must I attach the skirt fabric pieces to the bodice and then sew on the navy band? Would the navy band need some darts too? I want the navy band to sit just under the darts. Any advice/suggestions would be appreciated. Thanks!