I am new to RSD and there is something I am missing. There is a bit of a learning curve to say the least, but I am making progress. When I preview the site I am designing, all seems well on a medium sized screen and smaller. I have a large monitor, and as the screen size increases, things begin to fall apart. Where the images used to be I now have placeholders, and they seem to be out of place as well. I am sure it is something simple, but I have not figured out what it is. Assistance would be appreciated. Thanks in advance!

What you have done there is made changes on a specific breakpoint. What you need to do is select the farthest breakpoint and move the slider to the right of that. This is where you are supposed to make the first styles. Then you slowly move the slider to the left, adding breakpoints when your content brakes and then add your new styles for that breakpoint. Just keep repeating the process until your designs complete.

Thanks Scott,
I appreciate the assistance. I am gradually getting a handle on RSD. Slow process for me.