I have too much graphics in my future web site (I've done it in Flash format). But I don't know how to compress such files. Help me, please!

I would optimize all the graphics in fireworks first to a small format (I usually use gif adaptive) or if you must you can use jpegs. I would then remove any unused files in your Flash library right click the library and then "select unused files") Then compact it. File then click File-->save and compact. Hope this answeres your question.