96 civic engine started shaking and the check engine light came on. it is driveable but have no idea on where tho start looking to fix problem. installed new sparkplugs but no difference. it runs slower.

 

goto autozone and get your cel codes pulled or you can do it your self
http://www.honda-tech.com/showthread.php?t=1901557

tell us what codes you pull

 

Since the CEL came on, that means that the computer has stores a "trouble code" which may help considerably with the diagnosis. Most parts stores will hook up a code reader and read out the code for you for free. You can also do it yourself with a jumper wire and watching the light blink, but a OBDII code reader usually provides more detail. Get the code read and then report back.