Click here for sample guide of posting photos in CS. This is just one of the ways. It also applies to photobucket or any other website that stores photos. All you just need to know is how to get the link.
Now. When you go to the above website. Can you see all those link for the different size?
If Yes, Right Click on it, and select "Copy Link Address" depending on your web browser.
Now back to CS. When you want to post something here. you should be able to see a set of tools. Mouse over your mouse over all the icons. Find an icon that says "Insert Images". There should be a pop out saying "Please enter the URL of your image". Now what you have to do is just Right Click your mouse and Click on Paste.