How can I save a bitmap layer in fireworks? I tried using the export feature, but it exported everything except the bitmap background layer.
Also, how do I save a slice in png format, and which is the best format for using with web?
I'm not sure why your Fireworks file is not exporting the bitmap layer. Check the layer is visible (i.e. not hidden in the Layers palette) and you either had given it a corresponding slice or ensure that you have the "Include Areas without Slices" checkbox ticked in the Export dialogue box.
To save a slice in PNG format, first select the slice object within your image. In the Optimize palette choose PNG from the drop down. Fireworks offers three PNG formats - PNG 8, PNG 24 and PNG 32. These relate to different bit depths, which basically means the number of colours the PNG will support.
PNG 8 is best for images with a limited colour palette - like a logo. It uses an indexed colour palette similar to the way that the GIF format handles colours.
PNG 24 Supports a full palette of colours as JPEG does.
PNG 32 supports and alpha channel which allows you to use transparency effects in your image.
The best format for web depends on the type of image and how you want to use it. For logos and illustrations with limited colour palette or mechanical, flat areas of colour I would use PNG 8, unless you want transparency in which case use PNG 32. For photographic images I would use JPEG. PNG is lossless and therefore does not compress as efficiently as JPEG.
General tips about your needs;