Step 1: Open Fireworks, create new, once open, click File then Import. Import an image you would like to edit. My image is shown below.
Step 2: Select the Eraser Tool, displayed on the left side of the Fireworks tools. In the Properties area, on the bottom of the page, change the Size of the eraser to 30. It may all ready be at 30 or it may not be. Change the Edge to 2 and lower Eraser Opacity to 30. This will blur the background.
Step 3: Drag the eraser over the desired area you would like to blur. Note: Once you clicked the eraser, do not let go of the mouse until you have blurred what you wanted to blur. Otherwise when clicked again, blur will be at a different transparency.
The picture below is how the blur will appear.
Step 4: Repeat Step 3, to show that the unblurred area will appear seperately.
http://www.tutorialized.com/view/tutorial/Smartwebby-Fireworks-CS4-Guide-Photo-Blur-Effect/44430
