If you're trying to get the picture to appear inline with your post, like this...
...the easiest way to do this is to attach your picture(s) to your post and upload them to BF, then click on the name of the picture in the file manager window that appears; when your picture loads, highlight its URL, right click and "Copy," then return to your post and use the "Insert Image" tool. When it asks for the picture's URL, right click and "Paste." It took me more time than I'd like to admit to realize that pictures hosted on BF have an actual URL, and that the "Insert Image" tool recognizes this. For someone who's been on teh intarwebs more or less since 1992, I have a remarkable amount of trouble working with it sometimes.
Okay, so it's actually kind of complicated, but that's the way that I do it. Hopefully someone will come along and show how it can be done with one click of the mouse, thereby improving my internet experience and making me look like a moron simultaneously.
(Note that if I was doing this with a picture that I was hosting under my account, the thumbnail would appear at the bottom of the post. Since I'm jacking someone else's picture instead it's not an issue here.)
Irfanview is a free image editor that has pretty much all of the features the average person would need, including resizing and resampling. And did I mention that it's free?