If I understand you correctly - You need to remove part of an animated gif, add it to a photograph and then export the image as a jpeg, right?
You can edit frames in Fireworks (use the frames palette from the window menu). You can then edit the exact frame you require and drag-and-drop it into the photo. You can then edit it as you please as it will be a separate layer to your photo - then choose to export the image as a JPG
> file > export preview > choose jpg (select the level of compression) > export > save