Re: (kinda) new to sewing

Lots of great suggestions from Val!

A few more points of interest:
If you go to the the Saks website and look at the dress (it's by Marc 
Jacobs), click on the "click to enlarge image", then click on "zoom" in 
the pop-up window and it gives you a close-up of the trim detailing.  It 
looks as though the ribbon is sewn down with a decorative topstitch (as 
Val suggested) and the ribbon is used for the straps (Val, again! :)).

If you want the same number of seams as the original Marc Jacobs dress, 
here are my suggestions on modifying the Vogue pattern:
- transfer the side bust dart to the waist, then slash from that dart 
point up to the top of the bodice (add seam allowances and then you'll 
have the complete seam)
- slash the bodice down the centre and add seam allowances for the centre 
seam
- if you want to make the semi-circular cut-out, do so, but I would then 
suggest taking out 1/8" (more if you're bustier) from each side of the top 
of the middle seam (i.e., increase the seam allowance by 1/8" where the seam meets the 
bottom 
of the semi-circle, then taper back to your original seam allowance).  
Taking out this little bit of excess will prevent the dress from gaping at 
the top due to the cut-out (I learned this the hard way! :)).
- from the close-up shot of the MJ original, it looks like there is no 
side seam, but rather a "gusset" type strip of fabric running from 
mid-underarm; to achieve this, you'll have to slash both the front and 
back bodice near the sides where you want your seams to be, then join the 
side pieces you cut off at the side seam (this becomes more complicated if 
that seam is very curvy - in that case you have to transfer the intake to 
your new seams) and use those to cut out the side panels
- once you've added all these new seams to the bodice, you're going to 
have to divide the pleat intake of the skirt up and redistribute it to 
create the corresponding number of pleats. So, I think there's 5 pleats on 
the front of the MJ dress, so measure and add up the pleat widths of the 
Vogue pattern, divide by 5, and use that number as the width to mark the 
new pleats on the skirt pieces (the Vogue pattern piece for the skirt 
front is probably the "cut on fold" type, so this will be easier if you 
trace out both halves as one)

Of course, you don't have to make it look identical to the Marc Jacobs
design!  I think it would look smashing if the pleats (and corresponding
trim) were of varying lengths.

For ribbon, I highly recommend you check out Mokuba (a store devoted 
entirely to ribbons and trim!) on Queen St. W.  There's also some great 
books available through the Toronto Public Library system that would help 
you with the pattern drafting/modification.

I'm in Toronto, BTW, so I could probably give you a hand if needed.