It depends. Did you write the program yourself? If so, then do something like com.yourname.yourpackagename. If you didn't write it, use just the name of the package. For example, I wrote the No Hide Address Bar tweak so i made the package id be com.c0deh4cker.nohideaddressbar. I didnt write tcl, i just ported it, so i made the package id be tcl.