You can rotate images once you've placed them in a story. Learn how, here.
Below is a little information about why images sometime appear incorrectly rotated:
Some users have reported that when they place their images in Storypark the images end up rotated incorrectly. This is usually because the photo editing program they use doesn’t support auto-rotate.
Photos and videos can be recorded in either portrait (vertical) or landscape (horizontal) mode. Some cameras (like the cameras in smartphones) can detect the orientation and rotate images automatically. The way these cameras ‘remember’ the orientation is by attaching ‘EXIF’ data to the image. The problem occurs when you’ve downloaded them to your computer and opened them in a program that can’t read the EXIF data.
Some programs that support auto-rotate or can save them in the correct orientation are:
Google Photos (was Picasa) – download it free from Google here.
Adobe Photoshop (strips EXIF information from an image when you ‘Save For Web & Devices’)
Preview (Mac OS X)
Programs that don’t support auto-rotate are:
Windows Picture and Fax Viewer
Windows Photo Viewer
Microsoft Office Picture Manager
MS Paint (unless you open the image, click ‘save as’ and save in PNG format instead of JPEG.)
For more information you can read this article.