Sorry for the delay but I was hoping someone else would answer this thread. It's really very simple.
Select the 'Selector Tool' (arrow) click on the image (or bitmap) and notice the 8 squared bounding box. Click again and it changes to 8 rotational arrows. 'Mouse over' one of the corners and you can rotate the image at will.
Hope this helps. There's a lot more you can do, but this should help you for now.
Egg