If your ad contains only Black and Cyan inks you should be able to send the composite PDF and it will separate in the RIP at the publisher. If this is not waht the publisher wants, you need to get verys specific instructions from them. We can help you to understand those instructions if necessary.
The key here is that your images must be true grayscales or Black/Cyan duotones and you must not use any 4-color black elsewhere in the ad. Looking at your screen shot of the cyan plate it looks like the images are grayscale and OK, but your background gradient and black caption bars are showing cyan ink, so unless you used a cyan/black with no magenta and no yellow in them you have a problem. RGB colors cannot be used here.