On hubpages the image capsules will only float center (full-width) and right (half-width). Just click the arrow buttons until you get it where you want it.
There's currently no way to get an image to float left. Every once in a while someone makes this suggestion to staff on the forum, but so far staff hasn't given an answer on when they will permit left floating images, or why it was never included as an option in the first place. Just one of those mysteries I guess.