Putting the pieces together

When putting design boards together I'd like to learn how to clip out the background of each image to lay it over top of an other. I'm a new mac user as well, so if anyone could comment with a suggestion I'd be grateful. Polyvore is an excellent website but unfortunately I cant crop each image in any way I choose. I think if I could do that the design board below would look MUCH better.

So which image looks better? Which one conveys the idea better?

Anyway... the entryway I put together was inspired by the Cole and Sons Hummingbird wallpaper in the Ivory colour way. Paired with wainscotting and crown moulding painted out in Benjamin Moore's Mulberry. And the sumptuous green velvet chairs to provide a bit of visual interest/contrast. I kept the console, mirror, and scones the same finish to keep the look from going overboard.