Frosted glass effect/texture/filter/pattern in Adobe Fireworks?

I haven’t used Fireworks in a long time. I just use GIMP, but Fireworks should work.
In the example image you have provided, the distortion is so little I would just Blur it.

Way #1

try this:

1. Select the area you want to effect and copy it to a new layer.
2. Create a highly transparent black box narrow enough and centered vertically for top and bottom border.
3. Create top and bottom highly Transparent (like 25%) white strip as the border.
4. Place text.
5. blur copped image as desired.
6. (extra) Blur image under border horizontally even more like 100px more (depending on your image size)

But if you really want that rough glass distort effect, you should use GIMP, it’s free! and open source, why not?. These settings are pretty good on an image width of 1024px. Here you go!

Way #2

Example look closely

1. Open your image.
2. Use the Rectangle Select Tool over where you want.
3. Copy Ctrl + C then paste Ctrl + V.
4. Now in the Layers Panel, Right Click on the Pasted Layer and select Duplicate Layer.
5. Use the Paint Brush Tool set Color (white) Size (Large enough to make painting easy) and paint over that area.
6. Use the Rectangle Select Tool to select where you want the black part.
7. Use the Paint Brush Tool set Color (black) and paint the area.
8. In the Layers Panel set Opacity (25)
9. Select the Pasted Layer and blur Filters -> Blur -> Gaussian Blur set x (10), y (10).
10. In the Layers Panel, Right Click and select Duplicate Layer.
11. Select all Ctrl + Aand then press delete.
12. Now, Filter -> Noise -> Hurl set Random Seed (whatever), Randomization (60), Repeat (5).
13. Colors -> Desaturate set Lightness (on).
14. Filters -> Blur -> Gaussian Blur set x (2px), y (2px).
15. In the Layers Panel, Hide this layer and select Pasted Layer
16. Use the Box Select Tool over where you have the borders (hold Shift to select the other one). and Filter -> Blur -> Gaussian Blur set Horizontal (100), Vertical (0).
17. Now select all Ctrl + A and Filter -> Map -> Distort set x (10) and the hidden Layer, y (10) and the hidden layer, Displacement Mode (Cartesian), Edge Behavior (Smear).
18. Add text and change Opacity, and color

Way #3

Here is an example of what I got

1. Open the image.
2. Use the Rectangle Select Tool and drag over the image where you want to do that effect.
3. Copy Ctrl + C then paste Ctrl + V now select all Ctrl + A.
4. Now in the layers panel, Right Click on the top layer and select To New Layer.
5. Right Click on that layer select New Layer set Layer name (Cloud), Layer Fill Type (Transparent).
6. With the last layer you created selected Filters -> Render -> Clouds -> Plasma.
7. Set Turbulence (7) (Unless it is a very small image).

If you find your image is huge and need more noise, just:

1. Filters -> Map -> Make Seamless.
2. Use the Scale Tool set interpolation (None) Mark Keep Aspect.
3. Scale accordingly
4. Filters -> Map -> Tile to the size of your image, Done.
8. Filters -> Blur -> Gaussian Blur set Horizontal (5px) Virtcal (5px).
9. Filters -> Edge-Detect -> Sobel mark everything
10. Filters -> Blur -> Gaussian Blur set Horizontal (5px) Virtcal (5px).
11. Filters -> Map -> Displace set x (30, Cloud layer) y (30, Cloud layer), Distortion Mode (Cartesian) Edge Behaior (wrap).
12. Hide the Cloud and Image layer.
13. Use the Rectangle Select Tool Select where the pasted image is.
14. Unhide (so you can see the change) and select Cloud layer then Layer -> Crop Layer To Selection then re-hide Cloud layer.
15. Select Pasted image layer Blur (10px)
16. Filters -> Map -> Distort with the Cloud layer as X &Y, about 20 each, and mark Smear.
17. Create New Layer and select it.
18. Use the Paint Brush Tool set the Size large enough to paint over the selection. SetColor (Black)and then paint over it.
19. Use Select Rectangle ToolHold Ctrl + Click and Dragover the area where you do not want borders leaving selected where you want borders.
20. Use the Paint Tool set Color (white) and then paint over the area.
21. In the Layers Panel set Transparency (25%).
22. Select the copped image layer Filters -> Blur -> Gaussian Blur you want to un-mark Keep Aspect so you can set Horizontal (100) Virtcal (0).
23. Use the Text Tool set Font, Text, Size, Color and Layer Transparency.
24. exta, use the Select By Color Tool set Threshold (3) then Click on your text, it should now be selected.
25. Select pasted image layer, then Filter -> Blur -> Guassian Blur set x (40), y (40).

That’s the gist of it! Tween until it looks how you want.
Enjoy.
If you did’t get all that, ask me to explain it. good luck!