I can help, but first you need to read up on the subject. A good place to learn about this stuff is the Parts Express message board (
http://www.pesupport.com/cgi-bin/config.pl). Do a lot of searching before you post, as this had been covered many times. You'll need to identify what your needs are for size, spl, and bass response, as your design will inherently be a compromise between those three factors. Then download a speaker box modeling program (I prefer LinearTeam's WinISD, but there are many fine choices), and start trying out some enclosures.
That should get you pointed in the right direction. There are many books on the subject of speaker design, but I couldn't tell you which to try because I’ve never read any. There is a vast amount of information on the internet, too, so google is your friend. When you're ready, come back and ask away.
Where to find help? 
