Multiple website settings

Dear Sir,
I have downloaded Piwik and its amazing. I have one question about multiple website setting as I have same source code for multiple website… We have websites having same functionality so we use one source code and I want to integrate piwik with this source code. I have added website from Sites Management and get the JS code, added at it but its just recoding for one website not for others. It would be great help if you can help me.
Thank you

Your piwik code should be slightly different for each site (see: piwik_idsite = XXX;) where XXX is unique for each site.